Oral presentations

ORAL PRESENTATION

Oral presentations

OP 1

Development of potential anticancer agents

by coordination of bioactive molecules

to organometallic fragments

Wolfgang Kandioller1,2, Stephan Mokesch1, Carmen

Hackl1, Michael Jakupec1,2, Christian G. Hartinger3,

Bernhard K. Keppler1,2

1Institute of Inorganic Chemistry, University of Vienna, Waehringer

Strasse 42, 1090 Vienna, Austria. [email protected] Platform ‘‘Translational Cancer Therapy Research’’,

University of Vienna, Waehringer Strasse 42, 1090 Vienna, Austria3The University of Auckland, School of Chemical Sciences, Private

Bag 92019, Auckland 1142, New Zealand

Ru(II)-arene complexes are promising alternatives for the clinically

applied platinum-based chemotherapeutics. One approach is the

attachment of bioactive molecules to organometallic moieties,

leading to compounds with potential multi-targeted character which

are able to interact with different biological targets [1,2]. [1,4]-

Naphthoquinones are known for its broad range of biological

activities such as antibacterial, anti-inflammatory and anticancer

activities and the mode of action is supposed to be related to

reactive oxygen species (ROS) formation. [1,3]-Dioxoindan-2-car-

boxamides have shown promising topoisomerase inhibiting

properties and this compound class can be easily obtained by

rearrangement of the [1,4]-naphthoquinone backbone. With the aim

to develop novel metallodrugs with potential multi-targeted prop-

erties, these bioactive scaffolds were coordinated to organometallic

fragments. The synthesized ligands and the corresponding Ru(II),

Os(II) and Rh(III) complexes were characterized by standard ana-

lytical methods and their behaviour under physiological conditions,

binding affinity towards biomolecules, cytotoxicity in human can-

cer cell lines, ROS generating ability and further mode of action

studies will be discussed.

Financial support by the University of Vienna and the Johanna

Mahlke nee Obermann Foundation is gratefully acknowledged.

References1. Kilpin KJ, Dyswon PJ (2013) Chem Sci 4:1410–1419

2. Nazarov AA, Hartinger CG, Dyson PJ (2013) J Organomet Chem

751:251–260

OP 2

Effect of a hexacationic ruthenium complex as potential

anticancer drug on the cell metabolome studied

by 1H HR-MAS NMR spectroscopy

Martina Vermathen1, Lydia E.H. Paul1, Gaelle

Diserens2, Peter Vermathen2, Julien Furrer1

1Department of Chemistry and Biochemistry, University of Bern,

Freiestrasse 3, 3012 Bern, Switzerland2Departments of Clinical Research and Radiology, University

of Bern, 3010 Bern, Switzerland

A water soluble hexacationic Ruthenium complex [(p-cymene)6R-

u6(tpt)2(dhnq)3](CF3SO3)6 with tri-pyridyl-triazene (tpt) and

dihydroxy-naphthoquinone (dhnq) as bridging ligands was prepared

and tested for its anticancer activity and interaction with potential

biological targets [1]. The complex was found to be highly cytotoxic

against human ovarian carcinoma cells (A2780) with an IC50 value of

0.45 lM. To learn more about the specificity and the mechanism of

action, the effect of the complex on the metabolic profile of three

different human cell lines was studied by high resolution magic angle

spinning (HR-MAS) NMR spectroscopy. HR-MAS NMR allows

obtaining well resolved 1H NMR spectra from living cell suspensions

[2] well suited for chemometric analyses.

Cisplatin-sensitive and -resistant cancer cells (A2780 and

A2780cisR) as well as human embryonic kidney cells (HEK-293) as

healthy model cells were each incubated with the Ru-complex for 24

and 72 h, respectively. The corresponding cell suspensions were sub-

mitted to HR-MAS NMR yielding a total of 104 1H NMR spectra of

control and drug treated samples. Multivariate statistical analysis (PCA

and PLS) of the spectra indicated clear metabolic changes between

control and drug-treated cells for all 3 cell lines, as shown in the Figure

for tincub = 24 h. The changes were most pronounced for A2780 cancer

cells mainly due to lipids and choline containing compounds indicating

potential drug-induced membrane breakdown. The single components

responsible for the discrimination between all control and drug treated

groups are discussed in more detail in this presentation.

Financial supports by the University of Bern and SNF are grate-

fully acknowledged.

References1. Paul LEH, Therrien B, Furrer J (2012) J Biol Inorg Chem 17:1053

2. Griffin JL, Bollard M, Nicholson JK, Bhakoo K (2002) NMR

Biomed 15:375

123

J Biol Inorg Chem (2014) 19 (Suppl 2):S749–S764

DOI 10.1007/s00775-014-1159-9

OP 3

Fluorescent ‘‘crowdoxidation’’ probes

David G. Churchill11Department of Chemistry (Molecular Logic Gate Laboratory), Korea

Advanced Institute of Science and Technology, 373-1 Guseong-dong,

Yuseong-gu, Daejeon, 305-701, Republic of Korea.

[email protected]

The chalcogens, as individual atoms, can be incorporated into the

design of fluorescent (fluorogenic) molecules. Novel classes of

fluorophores can be produced and exploited for, not only sensing,

but also therapeutics and theranostics (e.g., GPx systems). So far,

we have produced four different chalcogen-containing molecular

motifs. A simple electron photoinduced electron transfer (PET)

donor–acceptor design is utilized. The rotation of the electron

donor is critical in fluorescence properties in these systems. Our

laboratory has reported the first well-defined molecular probe

involving chalcogen oxidation (benzothienyl–BODIPY) as the

chemical switch for fluorescence/optical changes. It serves as the

electron donor in a PET donor–acceptor design [1]. Our laboratory

first reported a probe in which there are multiple sites of oxidation

(multi-input) [2]. A total of four oxidation sites are possible here.

Our laboratory first synthesized a BODIPY diselenide probe [3]. It

is the second one, only, to behave as a reversible superoxide probe.

This probe involves BODIPY–Phenyl–Se–Se–Phenyl–BODIPY

attachments. The selenides are connected ortho in the electron

receptor to maximize the impact on sterics. The sensitivity,

selectivity, time response, cell studies, stability are all affirmative

and decent, or excellent. In the process of repairing a diselenide

probe for the non-substituted system, an unexpected reaction

occurred. This is the first annulation product of its class [4];

importantly, it is the first chalcogen annulation product known for

dipyrrins, or aryl-meso porphyrins, etc. The probe is an ‘‘off–on’’

fluorescent probe; it is reversible and \500 Da. The structure

shows large mean planarity and rigidity; the uniquely-placed

chalcogen atom is saddled halfway between the aryl ring and

chromophore. This results in a red-shifted emission band molecule

where, again, the molecule is kept small. Organoselenides also

feature in a chelation site in a BODIPY conjugate in a recent paper

devoted to modelling subsequent Fenton chemistry based on fer-

rous/ferric ion coordination and detection [5]. Financial support by

the National Research Foundation of Korea and the Center for

Catalytic Hydrocarbon Functionalizations, Institute for Basic

Science.

References1. Choi SH, Kim K, Jeon J, Meka B, Bucella D, Pang K, Khatua S,

Lee J, Churchill DG (2008) Inorg Chem 47:11071–11083

2. Singh AP, Mun Lee K, Murale DP, Jun T, Liew H, Suh Y-H,

Churchill DG (2012) Chem Commun 48:7298–7300

3. Manjare ST, Kim S, Heo, WD, Churchill DG (2014) Org Lett

16:410–412

4. Manjare ST, Kim J, Lee Y, Churchill DG (2014) Org Lett

16:520–523

5. Murale DP, Manjare ST, Lee Y-S, Churchill DG (2014) Chem

Commun 50:359–361

OP 4

Sulfite oxidase: A paradigm for the mechanistic

complexities and mysteries of metallo-enzymes

with multiple domains, subunits and cofactors

John H. Enemark, Gordon Tollin, Susan BorowskiDepartment of Chemistry and Biochemistry, University of Arizona,

Tucson, AZ 85721 USA

Human sulfite oxidase (hSO) is a complex enzyme that is essential for

normal neonatal neurological development. Each of the two identical

subunits of the homodimeric hSO protein possesses two domains that

are linked by a flexible polypeptide tether. One domain contains the

molybdenum cofactor and the other a b-type heme. The generally

accepted catalytic mechanism for the oxidation of sulfite to sulfate by

SO involves five different formal oxidation states for the Fe and Mo

centers and both oxygen atom transfer and electron transfer processes.

However, several recent studies of recombinant variants of hSO have

produced seemingly paradoxical kinetic, structural and spectroscopic

data that are not easily explained by previous mechanistic proposals.

We have developed a comprehensive model for the catalytic mech-

anism of hSO that involves extensive inter-domain conformational

changes of all five formal oxidation states of the Fe and Mo centers.

This mechanistic model provides a framework for interpreting pre-

vious results on hSO and for planning future research. In addition, this

model clearly shows that hSO is not just a medical curiosity related to

a rare inherited disorder. Rather, hSO is an excellent example of a

multi-cofactor, multi-subunit, multi-domain, multi-conformational

state metallo-enzyme whose properties have broad and general

importance for medicine and for bioinorganic chemistry.

OP 5

Molybdenum and tungsten enzyme’s active site models:

some new developments in dithiolene chemistry

Carola Schulzke1, Yulia B. Borozdina1, Christian

Fischer1, Ashta Chandra Ghosh,1 Muhammad Zubair2

1Institut fur Biochemie, Ernst-Moritz-Arndt-Universitat Greifswald,

Felix-Hausdorff-Str. 4, 17487 Greifswald, Germany2School of Chemistry, Trinity College Dublin, College Green, Dublin

2, Ireland. [email protected]

Some new developments in dithiolene molybdenum model chemistry,

in particular focusing on structural aspects of molybdopterin, will be

presented. These are, for instance, synthesis, characterisation and

reactivity of pyrane dithiolene complexes of molybdenum and tung-

sten and derivatives thereof. Chemical, electrochemical and catalytic

properties were studied in comparison in order to further understand

the role of the pyrane unit in molybdopterin. The pyrazine ring in

combination with the dithiolene moiety has been addressed sepa-

rately. Among intended outcomes of the various synthetic approaches,

some unexpected and pleasantly surprising observations were made

[1, 2]. These are for instance unusual binding motifs found crystal-

lographically (e.g. dithiolene-sulfur hydrogen bonds, interactions

involving the M=O moiety and packing motifs; Fig.), the discovery of

a very mild synthetic route to pentathiepins and the unexpectedly

facile oxidation of complexes by air.

S750 J Biol Inorg Chem (2014) 19 (Suppl 2):S749–S764

123

Generous financial support by the ERC is gratefully acknowledged

(project: MocoModels).

References1. Zubair M, Ghosh AC, Schulzke C (2013) Chem Commun

49:4343–4345

2. Doring A, Fischer C, Schulzke C (2013) Z Anorg Allg Chem

639:1552–1558

OP 6

The role of side chains in the fine tuning of metal

binding ability of peptides

Katalin Varnagy, Gizella Csire, Sarolta Timari,

Agnes David, Csilla KallayDepartment of Inorganic and Analytical Chemistry, University

of Debrecen, Egyetem ter 1, 4032 Debrecen, Hungary.

[email protected]

It is well known that peptides have high metal binding affinity, but

both the thermodynamic stability and the coordination geometry of

peptide complexes are very much influenced by the amino acid

sequence of the ligands. One field of our present research work is the

synthesis and investigation of polypeptides containing various side

chain donor groups, in which the coordination of side chain donor

atoms comes to the front and their sequences serve as the models of

different metalloproteins. These molecules include peptide fragments

of Cu, Zn-superoxide dismutase enzyme and amylin which is a

37-residue peptide hormone cosecreted with insulin by pancreatic b-

cells [1, 2].

We synthesized such series of multihistidine peptides in which the

systematic change of the amino acid sequence is carried out and the

equilibrium, structural and electrochemical parameters of their com-

plexes are determined. These molecules include oligopeptides built up

from 4 to 12 amino acid residues containing 2–4 histidines among

them. The thermodynamic, structural and electrochemical properties

of these peptides are primarily determined by the number and location

of histidyl residues. The presence of positively or negatively charged

and polar or bulky side chains of other amino acids in the neigh-

bourhood of the metal binding sites can, however, significantly

contribute to the above mentioned parameters of these complexes. To

understand the specific effects of these side chains aspartic acid,

serine or phenylalanine are inserted into the sequence of the multih-

istidine peptides [Ac-(HisXaa)n-His, Xaa=Ala, Phe, Asp, Ser etc.].

On the other side, the studies of amylin fragments (-ValArg-

SerSerAsnAsn-) and their mutants reveal that the presence of more

polar side chains (Ser, Asn etc.) in the peptide could result in the

formation of stable metal complexes despite the lack of any common

strongly coordinating donor functions.

In this work we demonstrate through the studies of the above

mentioned peptides those tendencies which finely regulate the equi-

librium, structural and electrochemical parameters of metal complexes.

Acknowledgement: The research was supported by the EU and co-

financed by the European Social Fund under the project ENVIKUT

(TAMOP-4.2.2.A-11/1/KONV-2012-0043)

References1. Timari S, Cerea R, Varnagy K (2011) J Inorg Biochem

105:1009–1017

2. Kallay C, David A, Timari S, Nagy EM, Sanna D, Garribba E,

Micera G, De Bona P, Pappalardo G, Rizzarelli E, Sovago I (2011)

Dalton Trans 40:9711–9721

OP 7

Transition metals alter the biological properties

of dithiocarbamates: formation of metal complexes

and the uses of metal–organic frameworks

Raymond W.-Y. Sun1, Ming Zhang1, Shan Deng2,

Alice S.-T. Wong3, Nikki P.-Y. Lee4

1Department of Chemistry, Shantou University, No. 243 Daxue Road,

Shantou, Guangdong 515063, People’s Republic of China.

[email protected] of Chemistry,3School of Biological Sciences and4Department of Surgery, The University of Hong Kong, Pokfulam

Road, Hong Kong

Various sulphur-containing molecules including dithiocarbamates and

an anti-alcoholism agent disulfiram have shown promising in vitro and

in vivo anti-cancer activities. Major hurdles in the development of these

molecules include the stability, bioavailability, specificity, drug detoxi-

fication and cellular resistance accounting for by the direct binding of

their active sulphurs to the thiol-containing peptides/proteins.

Different metal ions and their coordination compounds present

unique structural features and distinctive physical, chemical and

biological properties, thus rendering them irreplaceable roles over

common organic moieties in biological systems. By appropriate

selection of coordinating metal ions, dithiocarbamates can be tuned

and rationally designed to achieve different biological activities.

Moreover, metal can be used to construct biologically-relevant metal–

organic frameworks (MOFs). These materials can also be used as

carriers to enhance the bioavailability of the encapsulated materials.

In this work, we have demonstrated the alteration in physical prop-

erties and the anti-cancer/viral activities of various transition metal-

based dithiocarbamato complexes compared to that of their corre-

sponding dithiocarbamates. The encapsulating and sustained-release

properties of MOFs render to these dithiocarbamates and their related

complexes have also been reported.

Financial supports by Shantou University (2013 NTF13005),

General Research Fund (HKU 704812P), University Grants Com-

mittee of the Hong Kong Special Administrative Region are

gratefully acknowledged.

J Biol Inorg Chem (2014) 19 (Suppl 2):S749–S764 S751

123

References1. Zhang JJ, Lu W, Sun RWY, Che CM (2012) Angew Chem Int Ed

51:4882

2. Zhang JJ, Lok CN, Ng KM, Sun RWY, Che CM (2013) Chem

Commun 49:5153–5155

OP 8

Ruthenium complexes of redox-active intercalating

ligands as an emerging class of anti-cancer agents

Frederick M. MacDonnell, Nagham Alatrash,

Eugenia S. NarhDepartment of Chemistry and Biochemistry, University of Texas

at Arlington, Arlington, TX 76019, USA

The clinical success of cisplatin in cancer therapy has demonstrated

the tremendous potential of metal complexes as therapeutic agents,

however despite decades of subsequent research only a handful of

such metallodrugs exist, and most of these are simple derivatives of

cisplatin. We have reported on a new class of ruthenium complexes

which have low animal toxicity, good cytotoxicity and selectivity for

malignant over normal cells and which show *83 % regression in

H358 tumors implanted in nude mice compared to controls and a

doubling of lifetime [1, 2]. This paper will focus on examining the

mechanism of cytotoxicity which is correlated with their DNA

cleaving properties. The key structural feature common to the most

active complexes is the presence of a redox-active intercalating ligand

(see figure below) which can be bioreduced in situ. One redox product

is a reactive radical intermediate which is held in close juxtaposition

with the DNA backbone, and ultimately responsible for DNA

cleavage reaction. The pO2 is observed to affect the steady-state

concentration of the radical in a manner which results in enhanced

DNA cleavage as the pO2 is lowered. This has therapeutic implica-

tions as many tumor cells are often under hypoxic stress.

Financial support by the Robert A. Welch Foundation (Y-1301)

and US NCI-NIH is gratefully acknowledged.

N

N N

NN

N

N

N

RAIL

N

N N

NN

N

N

N

= {Ru(diimine)22+ fragment

References1. Yadav A, Janaratne T, Krishnan A, Singhal SS, Yadav S, Dayoub

AS, Hawkins DL, Awasthi S, MacDonnell FM (2013) Mol Cancer

Ther 12:643–653

2. Janaratne TK, Yadav A, Ongeri F, MacDonnell FM (2007) Inorg

Chem 46:3420–3422

OP 9

Ferritin: another ‘dialogue concerning the two chief

world systems’

Kourosh Honarmand-Ebrahimi, Peter-Leon

Hagedoorn, Wilfred R. HagenDepartment of Biotechnology, Delft University of Technology,

Julianalaan 67, 2628BC Delft, The Netherlands. [email protected]

Some four decades of intensive biochemical research on the ubiqui-

tous iron storage protein ferritin has provided a wealth of structural,

spectroscopic, kinetic, and thermodynamic data, from whose analysis

in recent years a sub-molecular picture of the mechanism of action is

beginning to emerge. Consensus, however, does not seem to be around

the corner yet, although the spectrum of viewpoints at this time appears

to condense into two well demarcated but mutually exclusive models:

(1) the unifying proposal that all ferritins essentially work according to

a single mode of operation (e.g. [1, 2]), versus (2) the diversifying

proposal that different classes of ferritins exhibit fundamental differ-

ences in their respective mechanisms (e.g. [3, 4]).

Drawing from Galileo’s format of a trialogue between two spe-

cialists and a layman to juxtapose arguments for/against Copernican

and Ptolemaic systems [5] we will present the main sets of data and

arguments for/against unifying and diversifying systems of ferritin

action with sufficient contrast to allow the informed layman to take

position. The debate centers around the question by what driving

force—after catalytic oxidation—the two iron ions leave the ferrox-

idase center of ferritin en route to core formation in the protein’s

cavity.

References1. Honarmand-Ebrahimi K, Bill E, Hagedoorn P-L, Hagen WR (2012)

Nat Chem Biol 8:941–948

2. Watts RK (2013) Chem Bio Chem 14:415–419

3. Turano P, Lalli D, Felli IC, Theil E, Bertini I (2010) Proc Natl

Acad Sci USA 107:545–550

4. Bradley J, Moore GR, Le Brun NE (2014) J Biol Inorg Chem. doi:

10.1007/s00775-014-11363

5. Gallileo G (1632) ‘‘Dialogo sopra I due massimi sistemi del

mondo’’ Landini Firenze

OP 10

Tuning the nuclease activity of macrocyclic copper

complexes

Jan Hormann1, Nora Kulak1

1Institute of Chemistry and Biochemistry, Freie Universitat Berlin,

Fabeckstr. 34/36, 14195 Berlin, Germany. [email protected]

The cleavage of DNA is of high importance for biotechnological and

therapeutic applications [1, 2]. The degradation of DNA in cancer

cells is among the applications that could be carried out by so-called

nucleases. Whereas there are a variety of natural enzymes available,

as synthetic chemists we seek for small metal complexes that do the

same job, but come with some advantages concerning stability, prize

and accessibility to rational design.

Some of the artificial metallonucleases used so far are based on the

macrocyclic ligand cyclen (1,4,7,10-tetraazacyclododecane).

Approaches for increasing the efficiency of such metallonucleases

comprise the design of multinuclear metal complexes and the

attachment of DNA intercalators and positively charged residues to

the ligand moiety in order to increase the affinity to DNA [3].

We show here, that the exchange of one of the nitrogen atoms in

the cyclen ligand by oxygen (oxacyclen) or sulfur (thiacyclen) has an


123

http://dx.doi.org/10.1007/s00775-014-11363

important impact on the oxidative cleavage activity of its copper

complexes (O [ S [ N) [4]. Recent results are also presented to show

that further derivatization in the ligand’s donor set and periphery

leads to an increase in efficiency. The knowledge acquired during

these studies allows us now to tune the nuclease properties of cyclen

copper complexes.

Financial support by the Deutsche Forschungsgemeinschaft (DFG)

is gratefully acknowledged.

References1. Hormann J, Perera C, Kulak N (2013) Nachr Chem 61:1003–1006

2. Wende C, Ludtke C, Kulak N (2014) Eur J Inorg Chem (in press).

doi:10.1002/ejic.201400032

3. Mancin F, Scrimin P, Tecilla P (2012) Chem Commun

48:5545–5559

4. Hormann J, Perera C, Deibel N, Lentz D, Sarkar B, Kulak N (2013)

Dalton Trans 42:4357–4360

OP 11

DNA-interacting molecular switches

Andreu Presa1, Guillem Vazquez1, Patrick Gamez1,2

1Departament de Quımica Inorganica, Facultat de Quımica,

Universitat de Barcelona, Martı i Franques 1-11, 08028 Barcelona,

Spain. [email protected] Catalana de Recerca i Estudis Avancats (ICREA), Passeig

Lluıs Companys 23, 08010 Barcelona, Spain

Photoactivated chemotherapy drugs provide the prospect to achieve

highly controllable activity with reduced side effects [1]. Photoacti-

vation of coordination compounds are commonly based on metal-

centred processes [2].

Dithienylcyclopentene (DTE) molecules undergo thermally irre-

versible cyclization reactions between colourless (open) and coloured

(closed) forms when stimulated with UV and visible light (see figure)

[3]. This closing/opening event gives rise to a contraction or expan-

sion of the molecule, respectively. For instance, the distance between

the methyl groups in 1,2-bis(2,5-dimethyl(3-thienyl))-3,3,4,4,5,5-

hexafluorocyclopent-1-ene decreases by 1.138 A upon ring closure

(figure).

In this presentation, a series of photoswitching metal complexes

obtained from DTE-based ligands will be described together with

their properties. Actually, in addition to the expected distinct optical

properties, the open and closed forms of such coordination com-

pounds exhibit different DNA-interacting properties.

Financial support by the Ministerio de Economıa y Competitivi-

dad (MINECO) of Spain (Project CTQ2011-27929-C02-01). COST

Action CM1105 is kindly acknowledged.

References1. Farrer NJ, Salassa L, Sadler PJ (2009) Dalton Trans 10690–10701

2. Szaciłowski K, Macyk W, Drzewiecka-Matuszek A, Brindell M,

Stochel G (2005) Chem Rev 105:2647–2694

3. Feringa BL (ed) (2001) Molecular switches. Wiley-VCH,

Weinheim

OP 12

Reversible transformation between cuboidal Fe4S4

and dinuclear Fe2S2 cores

Kazuki Tanifuji, Kazuyuki Tatsumi, Yasuhiro OhkiResearch Center for Materials Science, and Department of Chemistry,

Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya

464-8602, Japan

Splitting of the [Fe4S4] cluster core into two [Fe2S2] fragments has

not been realized in synthetic inorganic chemistry. On the other hand,

it has been proposed that the [Fe4S4] cubane in the fumarate nitrate

reductase regulatory protein is transformed to dinuclear [Fe2S2] cores

under O2, while the protein dissociates DNA [1]. A similar oxidative

decomposition of [Fe4S4] in Nif-IscA was postulated to occur gen-

erating [Fe2S2] cores [2].

In this presentation, we show a series of reactions displaying

interconversion between [Fe4S4] and [Fe2S2] core structures based

on the preformed all-ferric [Fe4S4]4+ cluster, [Fe4S4{N(SiMe3)2}4]

(1). Treatment of 1 with excess pyridine (py) or pyridine deriva-

tives (py-R) resulted in splitting of the cubane core to

[Fe2S2{N(SiMe3)2}2(py-R)2] (2). The 1H NMR spectra of the di-

nuclear products 2 in C6D5Cl show presence of 1 and py-R,

indicating that 2 and 1 are in equilibrium in solution. Conversely,

fusion of two [Fe2S2] cores of 2 was found to be facilitated by

B(C6F5)3, generating [Fe4S4{N(SiMe3)2}4] (1) and (Py-R)B(C6F5)3.

[Fe4S4] cores with lower oxidation states were formed by chemical

reduction of cluster 2. Treatment of 2 with 1.2 equiv of Na[C10H8]

in THF afforded [Fe4S4{N(SiMe3)2}4]2- (3), while an analogous

reaction of 2 with 0.5 equiv of Na[C10H8] gave rise to [Fe4S4{-

N(SiMe3)2}4]- (4).

Interestingly, while the reduced forms of [Fe4S4] clusters, 3 and 4,are intact in the presence of excess pyridine, the addition of excess

oxidant ([Cp2Fe]+) to the reaction systems readily gave [Fe2S2{-

N(SiMe3)2}2(py-R)2] (2), presumably via formation of all-ferric

[Fe4S4{N(SiMe3)2}4] (1). Thus, the all-ferric [Fe4S4]4+ state is

essential for dissociation of [Fe4S4] into [Fe2S2].

References1. Popescu C, Bates DM, Beinert H, Munck E, Kiley PJ (1998) Proc

Natl Acad Sci USA 95:13431–13435.

2. D. T. Mapolelo DT, Zhang B, Naik SG, Huynh BH, Johnson MK

(2012) Biochemistry 51:8071–8084

OP 13

Conversion of readout from transcriptional regulator

by electron transfer proteins

Hiroshi Nakaijma1, Souji Miyazaki2, Takaaki Itoh1,

Yoshihito Watanabe2

1Department of Chemistry, Nagoya University, Chikusa-ku,

464-8602, Nagoya, Japan2Reseach Centre of Materials Science, Nagoya University, Chikusa-ku,

464-8601, Nagoya, Japan. [email protected]

In a biological system there are various transcriptional regulator

proteins which evolved to detect environmental factors, control

appropriate biological events, and retain the homeostasis of living


123

http://dx.doi.org/10.1002/ejic.201400032

cells at the transcriptional level. The high, specific sensitivity of

these proteins is attractive for constructing novel bio-based sensor

modules. However, facile conversion of the biological readout from

the protein to a readily detectable signal is a major issue to be

solved before application. We have recently developed a signal-

transducing mechanism consisting of a pair of electron transfer (ET)

proteins [azurin and cytochrome c (Cyt c)] and a stimulus responsive

molecule that was introduced at the hydrophobic surface of azurin so

as to modulate inter-proteins interaction and the subsequent ET step

in the stimulus dependent manner [1]. In this study, we show

application of the signal-transducing mechanism to a transcriptional

regulator (figure). Thereby, the readout from the regulator is con-

verted to a change in the apparent ET rate between the ET proteins

[2]. The hydrophobic surface of azurin was chemically modified

with a double stranded oligo-DNA (DNA-Azu) that contains a rec-

ognition sequence of a carbon monoxide (CO) dependent

transcriptional regulator, CooA [3]. CooA showed reversible binding

to DNA-Azu, depending on CO. The apparent ET rate constant (kET)

for Cyt c and DNA-Azu was determined to be 6.2 9 104 M-1 s-1,

which was 16 folds smaller than that for Cyt c and wild type azurin

(1.0 9 106 M-1 s-1) [1], likely due to steric and electrostatic hin-

drance of DNA. The CooA binding to DNA-Azu partially recovered

the ET rate (5.0 9 105 M-1 s-1). We will discuss this behavior and

possible application to a modified electrode. We gratefully

acknowledge financial support by MEXT, Japan.

References1. Rosenberger N, Studer A, Takatani N, Nakajima H, Watanabe Y

(2009) Angew Chem Int Ed 48:1946–1949

2. Nakajima H, Miyazaki S, Itoh T, Hayamura M, Watanabe Y (2014)

Chem Lett (in press)

3. Thorsteinsson MV, Kerby RL, Conrad M, Youn H, Staples CR,

Lanzilotta WN, Poulos TJ, Serate J, Roberts GP (2000) J Biol Chem

275:39332–39338

OP 14

Contribution of each Trp residue towards the intrinsic

fluorescence of the Gia1 protein

Duarte Mota de Freitas, Matthew S. Najor, Kenneth W.

Olsen, Daniel J. GrahamDepartment of Chemistry and Biochemistry, Loyola University

Chicago, USA

Gia1 is the inhibitory G-protein that, upon activation, reduces the

activity of adenylyl cyclase. Comparison of the crystal structures of

Gia1 bound to GDP•AMF or GTPcS with that of the inactive, GPD-

bound protein indicates that a conformational change occurs in the

activation step centered on three switch regions. The contribution of

each tryptophan residue (W211 in the switch II region, W131 in the a-

helical domain, and W258 in the GTPase domain) toward the intrinsic

protein fluorescence was evaluated by using W211F, W131F and

W258F mutants. Regardless of the conformation, all three tryptophan

residues contributed significantly toward the emission spectra. When

activated by either GDP•AMF or GTPcS, the maximal fluorescence

scaled according to the solvent accessibilities of the tryptophan res-

idues, calculated from molecular dynamics simulations. In the

GDP•AMF and GTPcS, but not in the GDP, conformations, the

residues W211 and R208 are in close proximity and form a p-cation

interaction that results in a red shift in the emission spectra of WT,

and W131F and W258F mutants, but a blue shift for the W211F

mutant. The observed shifts did not correlate with the span of the

W211-R208 bridge but rather with the electrostatic energy of the

interactions in the various proteins. Trypsin digestion of the active

conformations only occurred for the W211F mutant indicating that

the electrostatic p-cation interaction blocks access to R208, which

was consistent with the molecular dynamics simulations. We there-

fore conclude that solvent accessibility and electrostatic interactions

account for the fluorescence features of Gia1.

OP 15

Label-free DNA-based biosensing using luminescent

metal complexes

Dik-Lung MaDepartment of Chemistry, Hong Kong Baptist University, Kowloon

Tong, Hong Kong. [email protected]

Oligonucleotides represent a versatile sensing platform due to their

ease of synthesis, sensitivity to particular analytes, low cost and

robust stability [1, 2]. Interest in DNA-based detection has exploded

in the scientific literature over the last few years. In particular, the use

of luminescent metal complexes as signal transducers in label-free

DNA sensing holds great promise as they are highly sensitive to

changes in the local environment, making them suitable to monitor

the DNA-switching event. Moreover, the application of luminescent

metal complexes in DNA sensing could further reduce the cost of

assay compared to the use of fluorescently-labelled oligonucleotides.

Transition heavy metal complexes possess salient advantages that

render them suitable for sensing applications: (1) their long emission

life-time allows their phosphorescence to be distinguished in highly

fluorescent media with the use of time-resolved spectroscopy, (2) they

usually display significant Stokes shifts which can prevent self-

quenching, and (3) their interaction with biomolecules and their

photophysical properties can be readily tuned without lengthy syn-

thetic procedures [3]. In this poster, I will present continuing progress

in the field of ‘‘label-free’’ luminescent based detection platform for a

variety of biologically and environmentally important analytes based

on oligonucleotides and luminescent metal complexes from our

research group.


123

References1. Du Y, Li B, Wang E (2012) Acc Chem Res 46:203–213

2. Ma DL, He HZ, Leung KH, Zhong HJ, Chan DSH, Leung CH

(2013) Chem Soc Rev 42:3427–3440

3. Zhao Q, Huang C, Li F (2011) Chem Soc Rev 40:2508–2524

OP 16

Copper(II), nickel(II) and zinc(II) binding ability

of the N-terminal fragments of amyloid-b peptide

Imre Sovago, Agnes GrenacsDepartment of Inorganic and Analytical Chemistry, University

of Debrecen, 4010 Debrecen, Hungary

Amyloid-b is a 40–43 residue peptide responsible for the develop-

ment of Alzheimer’s disease. The N-terminus of the peptide is reach

in histidyl residues and contains some other polar side chains which

enhance the metal binding ability of the peptide. Speciation and

characterization of the copper(II), nickel(II) and zinc(II) complexes

of the N-terminal hexadecapeptide fragment, Ab(1–16)-PEG, have

already been reported in our previous publications [1] but the elu-

cidation of the metal binding sites requires further studies. In this

work we report the synthesis of two nonapeptide domains of the

native peptide: Ab(1–9) and Ab(8–16) and their mutants. The

sequences of the six peptides studied are NH2-DAEFRHDSG-NH2,

NH2-DAAAAHAAA-NH2 and NH2-DAAAAAHAA-NH2 for

Ab(1–9) and Ac-SGAEGHHQK-NH2, Ac-SGAEGHAQK-NH2 and

Ac-SGAEGAHQK-NH2 for Ab(8–16). The results obtained from

combined potentiometric and spectroscopic (UV–vis, CD, ESR,

NMR and ESI–MS) studies will be presented here. Both thermo-

dynamic and structural data support the primary role of the amino

termini of peptides in copper(II) and nickel(II) binding. Moreover, it

can be unambiguously stated that the amino acid sequence of the

N-terminal domains of amyloid peptides is especially well suited for

the complexation with copper(II) ions as it is represented by the

figure showing the distribution of copper ions among the native and

two mutant peptides. The enhanced stability of the copper(II) com-

plexes was attributed to the secondary interactions of the polar side

chains of Asp, Glu, Ser and Arg residues present in the native

peptides.

β

The research was supported by EU and co-financed by the Euro-

pean Social Fund under the project ENVIKUT (TAMOP-4.2.2.A-11/

1/KONV-2012-0043).

Reference1. Arena G, Pappalardo G, Sovago I, Rizzarelli E (2012) Coord Chem

Rev 256:3–12

OP 17

pH dependence of amyloid-b–Cu(II) binding

and oligomerization kinetics

Jeppe T. Pedersen1, Christian B. Borg2, Kaare Teilum2,

Lars Hemmingsen3

1Department of Pharmacy, University of Copenhagen,

Universitetsparken 2, 2100 Copenhagen, Denmark.

[email protected] of Biology, University of Copenhagen, Ole Maaløes Vej

5, 2200 Copenhagen, Denmark3Department of Chemistry, University of Copenhagen,

Universitetsparken 5, 2100 Copenhagen, Denmark

Extracellular aggregation of amyloid-b peptides (Ab) is implicated in the

pathogenesis of Alzheimer’s disease. Metal ions such as Cu(II) can

promote aggregation of Ab on the millisecond–second time scale upon

binding [1, 2]. Hence, aberrant metal–Ab interaction may play a role in

development of AD. It is well-established that there are multiple coor-

dination states of Cu(II) in soluble Ab and the different states co-exist in a

dynamic equilibrium depending on the pH [3,4]. It is reasonable to think

that distinct Ab–Cu(II) species could have distinct oligomerization pro-

pensity. Here, we study the Cu(II) binding mechanism to Ab and the

subsequent oligomerization at different pH using stopped-flow fluores-

cence and light scattering in combination with NMR relaxation.

Financial support by the Villum Foundation is gratefully acknowl-

edged.

References1. Noy D, Solomonov I, Sinkevich O, Arad T, Kjaer K, Sagi I (2008) J

Am Chem Soc 130:1376–1383

2. Pedersen JT, Teilum K, Heegaard NHH, Østergaard J, Adolph

H-W, Hemmingsen L (2011) Angew Chem Int Ed 50:2532–2535

3. Drew SC, Noble CJ, Masters CL, Hanson GR, Barnham KJ (2009)

J Am Chem Soc 131:1195–1207

4. Dorlet P, Gambarelli S, Faller P, Hureau C (2009) Angew Chem Int

Ed 48:9273–9276

OP 18

Probing the efficacy of novel bismuth (III and V)

complexes as anti-leishmanial agents

Philip C. Andrews,1 Lukasz Kedzierski,2 Yih Ching

Ong1

1School of Chemistry, Monash University, Melbourne, VIC 3800,

Australia. [email protected] and Eliza Hall Institute of Medical Research, Parkville, VIC

3052, Melbourne, Australia

Even after 70 years, Leishmaniasis, the deadly parasitic disease

endemic in various forms across the developing world, is treated

primarily with two Sb(V) compounds; sodium stibogluconate and

meglumine antimoniate [1]. While effective, these drugs have sig-

nificant problems; treatment for visceral leishmania requires

intravascular or intramuscular injections daily for 28 days under strict

medical monitoring, and intracellular reduction processes involving


123

trypanothione produce active Sb(III) which is both highly toxic and

biodistributed [2]. Alternative drugs amphotericin B and pentamidine

are expensive and do not overcome the need for parenteral adminis-

tration or reduce the onset of severe side effects, and miltefosine,

while orally active, is also expensive and teratogenic [3].

Bismuth and its compounds are considered to have low systemic

toxicity in humans, while showing good antimicrobial activities. In this

context, we have been examining and assessing novel organometallic

and metal–organic Bi(III) and highly oxidising Bi(V) compounds for

their anti-leishmanial activity and toxicity towards human fibro-

blasts. This has involved synthesis using a range of ligand classes

(e.g. carboxylates, thiocarboxylates, thioamides, thioxoketonates,

hydroxamates), full characterisation, including crystal structures, and

an examination of stability in aqueous and biological environments

[4].

In this presentation we will report our most recent results in the

chemistry and biological assays, demonstrating the potential of bis-

muth compounds in treating leishmaniasis.

References1. Kedzierski L, Sakthianandeswaren A, Curtis JM, Andrews PC,

Junk PC, Kedzierska K (2009) Curr Med Chem 16:599–614

2. Demicheli C, Frezard F (2005) Drug Design Reviews-Online

2:243–249

3. Richard JV, Werbovetz KA (2010) Curr Opin Chem Biol 14:447

4. Andrews PC, Junk PC, Kedzierski L, Peiris, RM (2013) Aus J

Chem 13:6276–6279.

OP 19

Searching for new aromatic amine N-oxide metal

complexes as prospective agents against infectious

diseases

Esteban Rodrıguez1, Ignacio Machado1, Leonardo

Biancolino Marino2, Florencia Mosquillo3, Leticia

Perez3, Clarice Q. F. Leite2, Fernando R. Pavan2,

Lucıa Otero1, Dinorah Gambino1

1Catedra de Quımica Inorganica, Facultad de Quımica, Universidad

de la Republica, Gral. Flores 2124, 11800 Montevideo, Uruguay2Facultade de Ciencias Farmaceuticas, Unesp, 14801-902 Araraquara

(SP), Brazil 3Laboratorio de Interacciones Moleculares, Facultad de

Ciencias, Universidad de la Republica, Igua 4225, 11400 Montevideo,

Uruguay

Infectious diseases are major causes of human disease worldwide.

Despite the progress in efforts to control the spread of tuberculosis,

this ancient and currently re-emerging infectious disease still remains

a global public health issue. Chagas disease (American Trypanoso-

miasis) is a chronic infection caused by the protozoan parasite

Trypanosoma cruzi that affects about 10 million people in Latin

America.

Current chemotherapy for both diseases is inadequate and new

strategies for the discovery of new drugs are needed. Our group is

focused on the development of prospective metal-based drugs mainly

based on bioactive ligands and pharmacologically active metals. As

part of this work, we had previously developed Pd(II), Pt(II) and

Au(I) complexes of pyridine-2-thiol N-oxide (Hmpo). The ligand

blocks T. cruzi’s growth affecting all stages of the life cycle of the

parasite and showing low IC50 values. The complexes showed high

antitrypanosomal activities with adequate selectivity indexes. Results

suggested that the trypanocidal action of the complexes could mainly

rely on the inhibition of the parasite-specific enzyme NADH fumarate

reductase, main known parasite target for the free ligand.

In the search for new metal-based therapeutic tools against

tuberculosis and Chagas disease, and to further address the thera-

peutic potential of mpo metal complexes, two new octahedral

[MIII(mpo)3] complexes, with M = Ga or Bi, and two new Pd(II) and

Pt(II) heterobimetallic compounds [MII(L)(mpo)](PF6), with

L = ferrocene derivative, were synthesized and characterized in the

solid state and in solution. The compounds showed excellent activity,

both on the standard M. tuberculosis strain H37Rv ATCC 27294 (pan-

susceptible) and on five clinical isolates that are resistant to the

standard first-line anti-tuberculosis drugs isoniazid and rifampicin. In

addition, the complexes showed an enhancement of the anti-T. cruzi

activity compared with the parent compound.

These new derivatives are highly promising for the development

of prospective agents for the treatment of resistant tuberculosis and/or

Chagas disease.

References1. Vieites M, Smircich P, Guggeri L, Marchan E, Gomez-Barrio A,

Navarro M, Garat B, Gambino D (2009) J Inorg Biochem

103:1300–1306

2. Vieites M, Smircich P, Parajon-Costa B, Rodrıguez J, Galaz V,

Olea-Azar C, Otero L, Aguirre G, Cerecetto H, Gonzalez M, Gomez-

Barrio A, Garat B, Gambino D (2008) J Biol Inorg Chem 13:723–735

OP 20

The role of covalent heme to protein bonds

in the formation and reactivity of redox intermediates

of a bacterial peroxidase with high homology to human

peroxidases

Paul G. Furtmuller1, Markus Auer1, Andrea Nicolussi1,

Georg Schutz1, Marzia Bellei2, Gianantonio

Battistuzzi2, Christian Obinger1

1Department of Chemistry, Division of Biochemistry, VIBT-Vienna

Institute of BioTechnology, BOKU-University of Natural Resources

and Life Sciences, Muthgasse 18, 1190 Vienna, Austria.

[email protected] 2Department of Chemistry and Geology,

University of Modena and Reggio Emilia, 41100 Modena, Italy

Reconstructing the phylogenetic relationships of the evolutionary

lines of the mammalian peroxidases revealed the presence of novel

bacterial heme peroxidase subfamilies [1]. Recently, an ancestral

bacterial heme peroxidase of the peroxidockerin clade was shown to

possess halide oxidation activities similar to human peroxidases.

Moreover, the recombinant protein allowed monitoring of the auto-

catalytic (i.e. hydrogen peroxide-driven) formation of covalent heme

to protein bonds (which are also found in vertebrate peroxidases [2].

Here, for the first time, the direct impact of the covalent heme to

protein bonds on the formation and reactivity of all relevant redox

intermediates of this peroxidase is demonstrated by transient kinetic


123

measurements. Protein species with covalently bound heme were

compared with those having predominantly unmodified heme b.

We report the kinetics of binding of the low-spin ligand cyanide

and demonstrate the strong influence of this posttranslational modi-

fication on the redox reactions including formation of Compound I by

hydrogen peroxide as well as two- and one-electron reduction reac-

tions of Compound I to either the ferric enzyme or Compound II. The

presented data are discussed with respect to the known crystal

structures and kinetic data available from mammalian peroxidases.

This research was supported by the Austrian Funding Fund (FWF-

stand-alone project P20664 and the doctoral program BioToP- Bio-

molecular Technology of Proteins W1224).

References1. Zamocky M, Jakopitsch C, Furtmuller PG, Dunand C, Obinger C

(2008) Proteins 71:589–605

2. Auer M, Gruber C, Bellei M, Pirker KF, Zamocky M, Kroiss D,

Teufer SA, Hofbauer S, Soudi M, Battistuzzi G, Furtmuller PG,

Obinger C (2013) J Biol Chem 288:27181–27199

OP 21

Chlorite to chloride and O2 conversion: new lessons

from structural and mechanistic investigations

of chlorite dismutase

Christian Obinger1, Stefan Hofbauer1, Irene

Schaffner1, Katharina F. Pirker1, Georg Mlynek2,

Kristina Djinovic-Carugo2, Gianantonio Battistuzzi3,

Paul G. Furtmuller1

1Department of Chemistry, Division of Biochemistry,2Department for Structural and Computational Biology, Max F.

Perutz Laboratories, University of Vienna, 1030 Vienna, Austria3Department of Chemistry and Geology, University of Modena

and Reggio Emilia, 41125 Modena, Italy

Chlorite dismutases (Clds) are oligomeric heme b-dependent oxido-

reductases capable of catalyzing the conversion of chlorite (ClO2-)

into chloride and dioxygen (designation as ‘‘dismutase’’ is wrong and

should be eliminated in future).

This presentation compares two model Clds [1–3] from the two

main lineages that differ in oligomeric structure and subunit archi-

tecture. Here, we compare the available X-ray structures and discuss

the role of conserved heme cavity residues in maintenance of the

active site architecture as well as in catalysis [4, 5]. A reaction

mechanism is presented that underlines the important role of the

highly conserved distal arginine in keeping the transiently formed

intermediate hypochlorous acid in the reaction sphere for recombi-

nation with the oxoiron(IV) of Compound I. In this reaction a

covalent oxygen–oxygen bond is formed and O2 is released. Finally,

we discuss the close phylogenetic relationship between Clds and

recently discovered dye-decolorizing peroxidases [6].

Our research was supported by the Austrian Funding Agency

(FWF-doctoral program BioToP-Biomolecular Technology of Pro-

teins, W1224 and the stand alone project P25270).

References1. Kostan J, Sjoeblom B, Maixner F, Mlynek G, Furtmuller PG,

Obinger C, Wagner M, Daims H, Djinovic-Carugo K (2010) J Struct

Biol 172:331–342

2. Mlynek G, Sjoblom B, Kostan J, Fureder S, Maixner F, Gysel K,

Furtmuller PG, Obinger C, Wagner M, Daims H, Djinovic-Carugo K.

(2011) J Bacteriol 193:2408–2417

3. Hofbauer S, Gysel K, Mlynek G, Kostan J, Hagmuller A, Daims H,

Furtmuller PG, Djinovic-Carugo K, Obinger C (2012) Biochim Bio-

phys Acta Proteins Proteomics 1824:1031–1038

4. Hofbauer S, Bellei M, Sundermann A, Pirker KF, Hagmuller A,

Mlynek G, Kostan J, Daims H, Furtmuller PG, Djinovic-Carugo K,

Oostenbrink C, Battistuzzi G, Obinger C (2012) Biochemistry

51:9501–9512

5. Hofbauer S, Gysel K, Bellei M, Pirker KF, Hagmuller A, Schaffner

I, Mlynek G, Kostan J, Daims H, Furtmuller PG, Battistuzzi G, Dji-

novic-Carugo K, Obinger C (2014) Biochemistry 53:77–89

6. Hofbauer S, Schaffner I, Furtmuller PG, Obinger C (2014) Bio-

technol J 9:461–473

OP 22

Metal mobilization from waste hydroxide sludge

by sulfur oxidizing bacteria

Helmut Brandl1, Carlotta Fabbri1, Thomas Wuthrich2

1Institute of Evolutionary Biology and Environmental Studies,

University of Zurich, Winterthurerstrasse 190, 8057 Zurich,

Switzerland 2ALAB AG, In der Luberzen 5, 8902 Urdorf, Switzerland

When applying biological techniques (‘‘biohydrometallurgy’’) in the

mining of valuable metals such as copper and gold (‘‘bioleaching’’,

‘‘biomining’’), sulfur oxidizing microorganisms play a fundamental

role [1]. Sulfur oxidizers belong to the group of acidophilic microbes,

thrive on carbon dioxide, and form sulfuric acid as end product of

their metabolism resulting in the mobilization of elements from solid

materials. However, when treating metal-containing industrial waste,

high salt content along with high alkalinity might inhibit these acid-

loving microbes. Therefore, we investigated the physiological

potential of Halothiobacillus neapolitanus for the mobilization of

metals from waste hydroxide sludge originating from flue gas puri-

fication. H. neapolitanus is salt tolerant and metabolically active over

a pH range of 4–8.5 (with an optimum between 6.5 and 7), which

seems to be ideal for the biological treatment of alkaline waste

materials. Within a growth period of 10 days in a suspension of 10 g

sludge per liter, pH values dropped from 7 to 3.4. It was possible to

solubilize certain metals completely (e.g., Cd, Zn), whereas others

were mobilized to a smaller extent (e.g. Pb 30 %, Cu 50 %). Zn was

the major constituent (*95 %) of the leachate. By gradually

increasing bulk density, H. neapolitanus adapted to suspensions of

30 g sludge per liter. In summary, results showed that H. neapolitanus

can cope with alkaline salt-containing waste materials and mobilize

some metals to a high extent. In perspective, this might be the base for

a biological recovery of metals from hydroxide sludge, all the more

because the selective environment (high salt and metal content, low

pH) might allow a biological treatment of wastes under non-sterile

conditions.

Al Cd Cu Fe Ni Pb Zn

mob

iliza

tion

(%)

0

20

40

60

80

100


123

Reference1. Brandl H (2001) In: Rehm HJ (ed) Biotechnology, vol 10. Wiley-

VCH, Weinheim, pp 191–224

OP 23

Hydride binding to the active-site H-cluster of [FeFe]-

hydrogenase

Petko Chernev1, Camilla Lambertz2, Nils Leidel1,

Kajsa Sigfridsson1, Ramona Kositzki1, Thomas Happe2,

Michael Haumann1

1Department of Physics, Free University Berlin, Arnimallee 14,

14195 Berlin, Germany. [email protected] for Biochemistry of Plants, Department

of Photobiotechnology, Universitatsstrasse 150, Ruhr-University

Bochum, 44801 Bochum, Germany

[FeFe]-hydrogenase from green algae (HydA1) is the most efficient

enzyme for hydrogen (H2) production in nature. Its active site is a

unique six-iron center (H-cluster) composed of a [4Fe4S]H cluster

linked to a diiron unit, [2Fe]H. The molecular and electronic con-

figurations of the H-cluster need to be determined to understand the

specific restraints for high-rate H2 production to be implemented in

novel synthetic catalysts. We have probed the electronic configura-

tion of the H-cluster in purified HydA1 protein using site-selective

X-ray absorption and emission spectroscopy experiments for the first

time [1, 2]. This has provided novel and distinct spectroscopic sig-

natures, which were reproduced and interpreted by quantum

chemical calculations (DFT), thereby leading to specific H-cluster

model structures. The electronic configuration of several redox

intermediates thus was determined. We show that iron-hydride bonds

are absent in the oxidized and one-electron reduced states of the

H-cluster. Only in the two-electron (super-)reduced state an iron-

hydride bond could be directly detected. The hydride binding pos-

sibly occurs to the Fe–Fe bridging position at [2Fe]H. These results

suggest a catalytic cycle of [FeFe]-hydrogenases with at least three

main intermediates, involving protonation, hydride binding, and

electron transfer steps prior to the H2 formation chemistry. Our

methods open a new perspective for characterization of metal-

hydride species in (bio)inorganic chemistry.

MH acknowledges financial support by the DFG (Grants Ha3265/

2-2,/3-1, and/6.1), the BMBF (Grant 05K14KE1 within the Rontgen-

Angstrom Cluster), and Unicat (CoE Berlin).

References1. Chernev P, Lambertz C, Sigfridsson K, Leidel N, Kositzki R, Hsieh

C, Schiwon R, Yao S, Limberg C, Driess M, Happe T, Haumann M

(2014) manuscript submitted

2. Lambertz C, Chernev P, Klingan K, Leidel N, Sigfridsson K,

Happe T, Haumann M (2014) Chem Sci 5:1187–1203

OP 24

Probing the electron transfer mechanism of diiron-

carbonyl complexes relevant to the diiron sub-unit

of [FeFe]-hydrogenase

Guifen Qian2, Zhinyin Xiao1, Li Long1, Xiaoming Liu1, 2

1College of Biological, Chemical Sciences and Engineering, Jiaxing

University, Jiaxing, 314001 Zhejiang, China2Department of Chemistry, Nanchang University, Nanchang, 330031

Jiangxi, China. [email protected]

[FeFe]-hydrogenase and its mimicking chemistry have attracted a

great deal of attentions since its structural revelation about 15 years

ago due to its relevance to hydrogen energy, a promising energy

vector in future. Under physiological conditions, this enzyme

catalyses hydrogen evolution with zero-overpotential. It is appealing

to understand the intrinsic chemistry behind this feature. The con-

firmation of azodithiolate as the bridge of the diiron centre suggests

that PCET contributes certainly to decrease the overpotential [1].

Since either evolution or oxidation of hydrogen, two-electron per

molecule is involved. Therefore, there ought to be other explanation

for the zero-overpotential. Electrochemical investigations into the

mimics of the diiron sub-unit show that the reduction of the diiron-

carbonyl complexes may involve two-electron process despite a

single reduction wave observed often in their cyclic voltammo-

grams, that is, involving potential inversion caused by isomerisation

upon reduction [2]. By incorporating a ferrocenyl group into the

mimics to calibrate the number of electron [3], the ECE process is

clearly demonstrated and it is concluded that the inversed potential

(E2) can not be more positive than the first potential (E1). In con-

clusion, PCET and the potential inversion are the main causes for

the zero-overpotential of the enzymatic catalysis in hydrogen

evolution.

Financial support by Natural Science Foundation of China is


References1. Berggren G, Adamska A, Lambertz C, Simmons TR, Esselborn J,

Atta M, Gambarelli S, Mouesca JM, Reijerse E, Lubitz W, Happe T,

Artero V, Fontecave M (2013) Nature 299:66–70

2. Lounissi S, Zampella G, Capon JF, De Gioia L, Matoussi F,

Mahfoudhi S, Petillon FY, Schollhammer P, Talarmin J (2012) Chem

Eur J 18:11123–11138

3. Zeng X, Li Z, Xiao Z, Wang Y, Liu X (2010) Electrochem

Commun 12:342–345


123

OP 25

M–Purine(C8) constructs and their potential

applications in catalysis

Pablo J. Sanz Miguel, Andrea Cebollada, Alba Velle1Departamento de Quımica Inorganica, Instituto de Sıntesis Quımica

y Catalisis Homogenea (ISQCH), Universidad de Zaragoza-CSIC,

50009 Zaragoza (Spain). [email protected]

Coordination of transition metals to the imidazolic positions of pur-

ines or their derivatives has been widely studied in the cases of the N7

and N9 sites [1], but only scarcely for C8. There are few examples of

metal coordination to the C8 sites of N7,N9-methylated purines [2].

Houlton et al. prepared several C8-coordinated metal complexes with

purines by cyclometallation [3], with N7/N9 available for metal

coordination. In addition, only three examples of caffeine as C8-

monodentate ligand for Os, Ru, and Co have been reported [4]. Our

interest on C8-coordination of transition metals at purines is grounded

on their analogy with the N-heterocyclic carbene ligands, commonly

employed in catalysis.

We report on the first examples of twofold metal coordination to

both the C8 and N9 sites of purines, including examples of (1) cat-

alytic active Mn(purine-C8)n cyclic compounds, and (2) a stepwise

formation strategy of a Pt4,Pd4,Ag2 aggregate in which its central

skeleton is supported by dative bonds and strong intermetallic inter-

actions [5].

Financial support by the Spanish Ministerio de Economıa y

Competitividad (CTQ2011-27593, and Ramon y Cajal Program) is


References1. See e.g.: (a) Lippert B (2000) Coord Chem Rev 200–202:487–516;

(b) Houlton A (2002) Adv Inorg Chem 53:87–158

2. (a) Kascatan-Nebioglu A, Panzner MJ, Garrison JC, Tessier CA,

Youngs WJ (2004) Organometallics 23:1928–1931; (b) Skander M,

Retailleau P, Bourrie B, Schio L, Mailliet P, Marinetti A (2010) J

Med Chem 53:2146–2154; (c) Stefan L, Bertrand B, Richard P, Le

Gendre P, Denat F, Picquet M, Monchaud D (2012) ChemBioChem

13:905–912

3. See e.g.: (a) Price C, Elsegood MRJ, Clegg W, Rees NH, Houlton

A (1997) Angew Chem Int Ed 36:1762–1764; (b) Price C, Shipman

MA, Rees NH, Elsegood MRJ, Edwards AJ, Clegg W, Houlton A

(2001) Chem Eur J 7:1194–1201

4. (a) Krentzien HJ, Clarke MK, Taube H (1975) Bioinorg Chem

4:143–151; (b) Johnson A, O’Connell LA, Clarke MJ (1993) Inorg

Chim Acta 210:151–157; (c) Zhenga T, Suna H, Lua F, Harmsc K, Li

X (2013) Inorg Chem Commun 30:139–142

5. Cebollada A, Velle A, Sanz Miguel PJ (2014) unpublished results.

OP 26

Geometric and electronic structures of 5d

metallocorroles: Au, Pt, Os

Abhik GhoshDepartment of Chemistry, UiT-The Arctic University of Norway,

9037 Tromsø, Norway. [email protected]

Because of the size mismatch between the contracted N4 cores of

corroles and the large ionic radii of the 5d transition metals in their

lower oxidation states, the synthesis of 5d metallocorroles has been a

challenge for synthetic coordination chemists [1]. Against this back-

drop, gold corroles were synthesized recently and, in as yet

unpublished work in our laboratory, the first platinum and osmium

corroles have been synthesized. The work provides fascinating

examples of synthetic strategy, heavy-element mediated C–H acti-

vation, and ligand noninnocence, the last perhaps best exemplified by

a series of oxidized Pt corroles with the formula Pt(corrole•2-)ArAr0.A representative crystal structure is shown below. The potential

anticancer properties of the Pt complexes are currently being exam-

ined.

Reference1. Thomas KE, Alemayehu A, Conradi, J, Beavers CM, Ghosh A

(2012) Acc Chem Res 45:1203–1214

OP 27

Investigation of metal complexes-RNA interaction

Marianthi Zampakou1, Elena Alberti1, Michael P.

Coogan2, Daniela Donghi11Department of Chemistry, University of Zurich, Winterthurerstrasse

190, 8057 Zurich, Switzerland. [email protected] of Chemistry, Faraday Building, Lancaster University,

Bailrigg, Lancaster, LA1 4YB, UK

The use of metal complexes as therapeutic and diagnostic agents is

well acknowledged [1]. Depending on their chemical nature, these

complexes can interact with their biological target via covalent and

non-covalent binding [1]. The anticancer drug cisplatin and its

derivatives belong to the first class of compounds, and are believed to

mainly target DNA by preferentially binding to N7 atoms of guanine


123

bases [2]. Conversely, various complexes studied as potential bio-

imaging agents belong to the second class, and show luminescence

upon DNA intercalation [3]. In addition to DNA, metal complexes

can also target other biomolecules, including RNA [4]. The latter is

involved in several crucial biological processes and its structural

diversity makes it an attractive target for the development of struc-

ture-selective RNA targeting molecules [5]. For example, platinum

drugs can inhibit RNA dependent processes [4] and metal complexes

with potential in bio-imaging were shown to accumulate in RNA-rich

regions within the cell [6]. Nevertheless, information on metal con-

taining molecules binding to RNA is still scarce.

We are currently investigating the interaction of different classes

of metal complexes with RNA to rationalize the basis of structure-

selective recognition. We use as model systems RNA constructs that

contain structural features widespread in RNA, e.g. GU wobbles,

internal and terminal loops. On the one hand, we study RNA inter-

action with platinum drugs with a special focus on cisplatin and

oxaliplatin. On the other hand, we investigate the RNA binding ability

of mononuclear rhenium(I) metallo-intercalators [6]. The interaction

is studied by several techniques, including gel mobility shift assays,

UV–vis, luminescence and CD spectroscopy and mass spectrometry.

Special attention is given to NMR spectroscopy, which is used to both

localize the interaction site and to evaluate the structural changes

induced by metal complex binding.

Financial support by the Swiss National Science Foundation

(Ambizione fellowship PZ00P2_136726 to DD), by the University of

Zurich (including the Forschungskredit FK-13-107 to DD) and within

the COST Action CM1105 is gratefully acknowledged.

References1. Ma D-L, He H-Z, Leung K-H, Chan DS-H, Leung C-H (2013)

Angew Chem Int Ed 52:7666–7682

2. Alderden RA, Hall MD, Hambley TW (2006) J Chem Educ

83:728–734

3. Zeglis BM, Pierre VC, Barton JK (2007) Chem Commun

4565–4579

4. Chapman EG, Hostetter AA, Osborn MF, Miller AL, DeRose VJ

(2011) Met Ions Life Sci 9:347–377

5. Guan L, Disney MD (2012) ACS Chem Biol 7:73–86

6. Thorp-Greenwood FL, Coogan MP, Mishra L, Kumari N, Rai G,

Saripella S (2012) New J Chem 36:64–72

OP 28

Cyanide detoxification by molybdenum sulfur

complexes

Sigridur G. Suman1,2, Johanna M. Gretarsdottir1,

Thorvaldur Snæbjornsson1, Gerdur R. Runarsdottir1,

Paul E. Penwell2, Shirley Brill3, Carol Green3

1Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavik,

Iceland2Physical Sciences Department, SRI International, 333 Ravenswood

Avenue, Menlo Park, CA 94025, USA3Biosciences Department, SRI International, 333 Ravenswood

Avenue, Menlo Park, CA 94025, USA. [email protected]

Thiocyanate is a product of a biocatalytic reaction of cyanide and

sulfur by the rhodanase enzyme in the liver. Mechanistic studies

in vitro of the rhodanase catalyzed reaction of cyanide and thiosulfate

showed the reaction takes place by a conformational change of the

enzyme and metal assisted thiosulfate binding. The rate limiting step

of this reaction is the rupture of the sulfur–sulfur bond in thiosulfate

[1]. Natural sulfur substrates are quickly depleted at toxic levels of

cyanide. Thiosulfate is commonly administered with cyanide

treatments to facilitate thiocyanate formation since it does not affect

oxygen carrying capacity in smoke inhalation victims [2–3]. We

describe our approach to catalytically transfer sulfur from thiosulfate

to cyanide to facilitate thiocyanate formation, using well-tolerated

compounds in small amounts to minimize toxicity without sacrificing

oxygen transport. Data for spontaneous and catalytic sulfur transfer

reactions will be presented along with results from toxicity and effi-

cacy studies. In one instance we show near complete elimination of

cyanide from solution in 20 min, in a reaction of cyanide with thio-

sulfate solutions containing 10 mol% of a molybdenum sulfur

complex. The molybdenum sulfur complexes were shown non-toxic

in hepatocytes, and safe dose in mice was measured as 0.5 g/kg.

Financial support by the University of Iceland Research Fund, and

NIH NINDS Grant No. 5R21NS067265 is gratefully acknowledged.

References1. Leininger K, Westley J (1968) J Biol Chem 243:1892–1899

2. Ivankovich AD, Braverman B, Kanuru RP Heyman HJ Paulissian R

(1980) Anesthesiology 52:210–216

3. Baud FJ (2007) Hum Exp Toxicol 26:191–201

OP 29

Metal complexes as molecularly-targeted agents against

protein–protein interactions

Hai-Jing Zhong1, Li-Juan Liu1, Daniel Shiu-Hin Chan2,

Dik-Lung Ma2, Chung-Hang Leung1

1Department of Chemistry, Hong Kong Baptist University, Kowloon

Tong, Hong Kong, China2State Key Laboratory of Quality Research in Chinese Medicine,

Institute of Chinese Medical Sciences, University of Macau, Macao,

China

Protein–protein interactions (PPIs) are ubiquitous in essential bio-

logical processes such as cell proliferation and differentiation, host-

pathogen interactions, and signal transduction pathways [1]. Pio-

neering advances in the field of interactomics have uncovered new

networks of protein interactions within cells, with estimates for the

size of the interactome ranging up to 650,000 PPIs [2]. Hence, PPIs

have emerged as attractive targets in medicinal chemistry and drug

discovery [3]. Meanwhile, transition metals possess variable oxida-

tion states and molecular geometries that enable the design of

intricate coordination sphere architectures. The ability to arrange

organic ligands in a precise three-dimensional arrangement around

the metal centre can be harnessed to generate unique scaffolds for

recognizing the binding sites of proteins. Due to the adverse side

effects associated with ‘‘shotgun’’ cytotoxic metal complexes such as

cisplatin and its analogues, there has been a recent upsurge in interest

in the development of kinetically-inert metal complexes as molecu-

larly-targeted agents against enzymes or PPIs [4–7]. We present

recent examples of biologically active, kinetically-inert metal


123

complexes developed by our group, and highlight possible future

directions for this exciting field. Financial support by the University

of Macau is gratefully acknowledged.

References1. Lievens S, Eyckerman S, Lemmens I, Tavernier J (2010) Expert

Rev Proteomics 7:679–690

2. Stumpf M, Thorne T, de Silva E, Stewart R, An H, Lappe M, Wiuf

C (2008) Proc Natl Acad Sci USA 105:6959–6964

3. Wells J, McClendon C (2007) Nature 450:1001–1009

4. Meggers E (2011) Angew Chem Int Ed 50:2442–2448

5. Leung CH, Zhong HJ, Yang H, Cheng Z, Chan DS, Ma VP, Abagyan

R, Wong CY, Ma DL (2012) Angew Chem Int Ed 51:9010–9014

6. Zhong HJ, Leung KH, Liu LJ, Lu L, Chan DSH, Leung CH, Ma DL

(2014) ChemPlusChem (in press)

7. Leung CH, He HZ, Liu LJ, Wang M, Chan DSH, Ma DL (2013)

Coord Chem Rev 257:3139–3151

OP 31

Lanthanide complexes as tools for structural biology

Bim Graham1, James D. Swarbrick1, Michael D. Lee1,

Phuc Ung1, Sandeep Chhabra1, Choy Theng Loh2,

Thomas Huber2, Gottfried Otting2

1Monash Institute of Pharmaceutical Sciences, Monash University,

Parkville, VIC 3052, Australia. [email protected] School of Chemistry, Australian National University,

Canberra, ACT 0200, Australia

The tagging of proteins with paramagnetic lanthanide ions produces

large effects that are observable in NMR spectra, including pseudo-

contact shifts, paramagnetic relaxation enhancements and residual

dipolar couplings [1, 2]. These effects provide valuable structural

restraints to expedite protein structure determination and facilitate

structure analysis of protein–protein and protein–ligand interactions.

In addition, the attachment of pairs of gadolinium complexes to

proteins enables highly accurate distance measurements to be made in

protein assemblies via EPR spectroscopy [3]. Our group has devel-

oped a range of new tagging reagents and strategies for attaching

lanthanide ions to proteins in a site-specific manner, which have

greatly facilitated such structural studies. This presentation will

describe the synthesis, testing and utilization of some of our most

successful designs and approaches.

Financial support by the Australian Research Council is gratefully

acknowledged, including a Future Fellowship to B.G.

References1. Otting G (2010) Annu Rev Biophys 39:387–405

2. Keizers PHJ, Ubbink M (2011) Prog Nucl Magn Reson Spectrosc

58:88–96.

3. Yagi H, Banerjee D, Graham B, Huber T, Goldfarb D, Ottin G

(2011) J Am Chem Soc 133:10418–10421

OP 32

Expanding nature’s toolbox with artificial

metalloenzymes

Jorg Eppinger1, Johannes Fischer1, Anna Zernickel1,

Arwa Makki11Division of Physical Sciences and Engineering and KAUST

Catalysis Centre (KCC), King Abdullah University of Science

and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.

[email protected]

Artificial metalloenzymes are expected to combine enzymatic selec-

tivity with the broad range of catalytic motifs provided by

homogeneous catalysts. Using specifically designed metal-conjugated

affinity labels to introduce metal centres into the binding pocket of

cysteine proteases, we were able to overcome the lack of structural

definition, which tends to hamper catalytic selectivity. Experimental

results proof, that the protein ligand induces enantioselectivities. The

novel modular platform and the in situ protocol allow fast generation

of diverse libraries of organometallic enzyme hybrid catalysts (see

figure) [1].

Site-selective orthogonal incorporation of metal binding unnatural

amino acids (UAA) into a host protein represents another novel tool

to create catalytically active metalloenzymes in vivo. The incorpo-

rated UAA provides stable ligation of late transition metals or serves

as an anchoring point to selectively conjugate metal chelating

motives to the host protein. This presentation details our studies on

the development of an optimized fluorescent host protein (mTFP*)

with minimized metal binding affinity and its conversion into an

artificial metalloenzyme through UAA incorporation and specific

UAA-metal conjugation. X-Ray crystallographic studies, post-trans-

lational modification (e.g. CuAAC) and catalytic tests for

asymmetric cyclo-addition and Pd-catalyzed cross-coupling reactions

are presented.

Financial support by the King Abdullah University of Science and

Technology, KAUST (faculty baseline fund and KAUST-GCR pro-

ject FIC/2010/07) is gratefully acknowledged.

Reference1. Reiner T, Jantke D, Marziale AM, Raba A, Eppinger J (2013)

ChemistryOpen 2:50–54


123

OP 33

Synthesis of fac-{99(m)TcO3}+ complexes: activation

of [99(m)TcO4]2 by phosphonium cations

Henrik Braband, Michael Benz, Roger AlbertoDepartment of Chemistry, University of Zurich, Winterthurerstrasse

190, 8057 Zurich, Switzerland. [email protected] is a very practical nuclide for nuclear medical applications due

to its availability from generators, its short physical half-life time

(6 h), and the emission of low energy c-rays (140.5 keV). We are

aiming at a general understanding of the reactivity of technetium at its

highest oxidation state +VII. Our research foremost focuses on

compounds containing the fac-{99(m)TcO3}+-core, due to its inter-

esting chemical reactivities ((3+2)-cycloaddition with alkenes) [1].

This reactivity enables an innovative approach for the synthesis of

novel radioconjugates [2]. Recent developments, based on the inter-

action of phosphonium salts with the robust [99(m)TcO4]- anion in

neutral water, led to a simple procedure for the synthesis of

[99mTcO3(tacnR)]+ type complexes (tacnR = 1,4,7-triazacyclononane

or derivatives) [3]. Due to this new approach fac-{99mTcO3}? com-

plexes are now available in high yields and purity for stereoselective

labeling of biomolecules. The potential of the new bioconjugation

strategy has been demonstrated by labeling of a series of different

vectors (pharmacophores, non-natural amino acids, and carbohy-

drates) [4]. Furthermore, the labeling via (3?2)-cycloaddition has

been established as a novel procedure for the labeling of silica based

particles, which will help to gain more detailed in vivo data of silica

(nano)particles by non-invasive radioimaging, in the future [5].

Tc

OOO

N NNH

HH

R

Tc

OOO

N NNH

HHR

+

R = pharmacophores, amino acids, carbohydrates (nano)particles

References1. Pearlstein RM, Davison A (1988) Polyhedron 7:1981–1989

2. Braband H, Tooyama Y, Fox T, Alberto R (2009) Chem Eur J

15:633–638

3. Braband H, Benz M, Tooyama Y, Alberto R (2014) Chem Com-

mun 50:4126–4129

4. Braband H, Tooyama Y, Fox T, Simms R, Forbes J, Valliant, JF,

Alberto R (2011) Chem Eur J 17:12967–12974

5. Wuillemin, MA, Stuber WT, Fox T, Reber MJ, Bruhwiler D,

Alberto R, Braband H (2014) Dalton Trans 43:4260–4263

OP 34

Alkalimetal controlled DNA nanoswitch

Celia Fonseca Guerra1, Jordi Poater1, Marcel Swart1,2,

F. Matthias Bickelhaupt1

1Department of Theoretical Chemistry, VU University Amsterdam,

1081 HV Amsterdam, The Netherlands2Institut de Quımica Computacional, Universitat de Girona, 17071

Girona, Spain. [email protected]

The self-assembly capacity of DNA has been an inspiration in the

field of supramolecular chemistry. We show with dispersion-corrected

density functional theory that DNA itself can be used as a nanoswitch,

able to alternate between three states (weak, moderate and strongly

bound). The suitable DNA base pair to act as the switch is the

Watson–Crick GC base pair. Substitution of H8 at the six-membered

ring of the purine by OH enables via protonation or deprotonation to

obtain the switching capacity. This capacity is also observed when the

switching aggregate is addressed through coordination of alkali metal

cations to OH instead of protons. The switching behavior is still

preserved when the subsitituent is linked to the DNA base pair via

an acetylene linker (26 A) turning the substituent into a remote

control. The switching could therefore pass through a membrane

allowing for different experimental conditions of the controller and

the switch. The last step in the computational design of a DNA

switch was to introduce the switch into a DNA helix and ‘‘sub-

merge’’ it into different solvents. This computational investigation

of the artificial DNA nanoswitch showed that the switch conserves

its switching capacities under experimental conditions which in

general involve solvation.

Financial support by the NRSC-C, NWO, MICINN and HPC-

Europa2 is gratefully acknowledged.

References1. Fonseca Guerra C, van der Wijst T, Bickelhaupt FM (2006) Chem

Eur J 12:3032–3042

2. Fonseca Guerra C, Szekeres Z, Bickelhaupt FM (2011) Chem Eur J

17:8816–8818

3. Poater J, Fonseca Guerra C, Swart M, Bickelhaupt FM, submitted

OP 35

The diverse functions of calcium in natural water

oxidation

Dimitrios A. Pantazis, Marius Retegan, Vera Krewald,

Frank Neese, Nicholas CoxMax Planck Institute for Chemical Energy Conversion, Stiftstr.

34–36, 45470 Mulheim an der Ruhr, Germany

Natural water oxidation, carried out by an inorganic Mn4CaO5 cluster

embedded in the enzyme photosystem II of photosynthetic organisms,

underpins all oxygenic life on earth [1]. Among the many poorly

understood aspects of this process, which serves as the ultimate blueprint

for synthetic efforts towards development of synthetic water splitting

catalysts, is the role of calcium: why does the catalyst depend critically

on calcium for its function, and why is natural water oxidation inhibited

by very similar cations, even though they may be structurally incorpo-

rated in the catalytic cluster? We address these questions by combining

recent results from spectroscopy (EPR/ENDOR), information from

kinetics measurements, and extensive theoretical modelling of photo-

system II and its oxygen evolving complex [1–4]. Our results suggest

that the calcium ion satisfies not one but several diverse requirements,


123

which are electronic as much as structural in nature. Most importantly,

calcium simultaneously modulates the properties of not only the

Mn4CaO5 cluster itself, but also of the redox-active tyrosine residue that

mediates electron transfer from the water oxidation site to the photo-

driven charge separation site of the enzyme.

References1. Cox N, Pantazis DA, Neese F, Lubitz W (2013) Acc Chem Res

46:1588–1596

2. Pantazis DA, Ames W, Cox N, Lubitz W, Neese F (2012) Angew

Chem Int Ed 51:9935–9940

3. Retegan M, Neese F, Pantazis DA (2013) 9:3832–3842

4. Retegan M, Cox N, Lubitz W, Neese F, Pantazis DA (2014) Phys

Chem Chem Phys. doi:10.1039/C1034CP00696H

OP 36

Engineering biointerface with controlled cell adhesion

towards cancer diagnostics

Gao Yang1, Pengchao Zhang1, Xueli Liu1, Hongliang

Liu1, Shutao Wang1

1Technical Institute of Physics and Chemistry of the Chinese

Academy of Sciences, Beijing 100190, China. [email protected]

Circulating tumor cells (CTCs) have become an emerging ‘‘bio-

marker’’ for monitoring cancer metastasis and prognosis. Although

there are existing technologies available for isolating/counting CTCs,

the most common of which using immunomagnetic beads, they are

limited by their low capture efficiencies and low specificities. By

introducing a three-dimensional (3D) nanostructured substrate—spe-

cifically, a silicon-nanowire array coated with anti-EpCAM—we can

capture CTCs with much higher efficiency and specificity. The con-

ventional methods of isolating CTCs depend on biomolecular

recognitions, such as antigen–antibody interaction. Unlikely, we here

proposed that nanoscaled local topographic interactions besides bio-

molecular recognitions inspired by natural immuno-recognizing

system. This cooperative effect of physical and chemical issues

between CTCs and substrate leads to increased binding of CTCs,

which significantly enhance capture efficiency. Recently, we have

also developed a 3D cell capture/release system triggered by aptamer

enzyme, electrical potential and Temperature, which is effective and

of ‘‘free damage’’ to capture and release cancer cells. The bio-inspired

interfaces of cell capture and release open up a light to rare-cell based

diagnostics, such as CTCs, fetal cells, stem cell and so on.

Financial support by the Chinese Academy of Sciences is grate-

fully acknowledged.

References1. Liu X, Wang ST(2014) Chem Soc Rev 43:2385–2401

2. Liu H, Liu X, Wang ST et al (2013) Adv Mater 25:922–928

3. Jin J, Wang ST, Liu DS et al (2013) Adv Mater 25:4714–4717

4. Liu H, Li Y, Wang ST et al J Am Chem Soc 135:7603–7609

5. Zhang PC, Chen L, Zhou J, Wang ST et al (2013) Adv Mater

25:3566–3570

6. Wang ST, Liu K, Liu J et al (2011) Angew Chem Int Ed

50:3084–3088

OP 37

A comprehensive platform to investigate protein-metal

ion interactions by affinity capillary electrophoresis

(ACE)

Hassan A. AlHazmi1, Markus Nachbar1, Mona

Mozafari Toshizi1, Sabine Redweik1, Sami El Deeb2,

Deia El Hady3,4, Hassan M. AlBishri3, Hermann

Watzig1

1Institute of Medicinal and Pharmaceutical Chemistry, University

of Braunschweig, Germany2Department of Pharmaceutical Chemistry, Al-Azhar University-

Gaza, Gaza, Palestine3Chemistry Department, Faculty of Science-North Jeddah, King

Abdulaziz University, Jeddah, Saudi Arabia4Chemistry Department, Faculty of Science, Assiut University,

71516-Assiut, Egypt

Affinity Capillary Electrophoresis (ACE) provides an important

enhancement to characterize molecular interactions. In exciting

recent studies, the influence of various metal ions, including Li?,

Na?, Mg2?, Ca2?, Ba2?, Al3?, Ga3?, La3?, Pd2?, Ir3?, Ru3?, Rh3?,

Pt2?, Pt4?, Os3?, Au3?, Au?, Ag?, Cu2?, Fe2?, Fe3?, Co2?, Ni2?,

Cr3?, V3?, Mn2?, MoO42- and SeO3

2- was investigated by ACE,

giving deep insight into the functional interactions between these

species and biomolecules. The predominant role of ACE is in the

early screening stage when binding and non-binding compounds are

sorted out. The requirements for sample amount and purity are low,

but high precision of binding information in reasonable short ana-

lysis times can be expected [1]. ACE can now be performed in

*5 min including rinsing procedures. An excellent precision, cor-

responding to RSD % of 0.2–1.0 % was achieved. Long term

stability and appropriate method transfers have also been estab-

lished. The capillary manufacture batch, the type of temperature

controlling tool, the purity of running buffer constituents and the

quality of the ligands involved, including their stability, have been

identified as main parameters for robustness. Further ACE key

method development parameters include protein concentration,

length of injected plug, applied voltage, and the choice of the

regression method [2]. Now we not only provide a generic concept

and experimental conditions for all relevant metal ions to be

investigated, which could be easily enhanced to each and every

further species, but we also provide reference values for character-

istic interactions to a set of reference proteins. These concepts have

already been successfully applied for a number of applications,

namely Extracellular-signal Regulated Kinase (ERK), dehydrins

(metal-ion storing plant proteins), potentially Ca2? binding peptides

and transferrin.

References1. AlHazmi H, El Deeb S, Nachbar M, Redweik S, AlBishri HM, Abd

El-Hady D, Watzig H Submitted to electrophoresis, manuscript no.

elps.201400064

2. El Deeb S, Watzig H, El-Hady D (2013) Trends Anal Chem

48:112–131


123

http://dx.doi.org/10.1039/C1034CP00696H

OP 38

Specific recognition of DNA depurination

by a luminescent terbium(III) complex

Xiaohui Wang1,3, Xiaoyong Wang2, Zijian Guo1

1State Key Laboratory of Coordination Chemistry, School

of Chemistry and Chemical Engineering, Nanjing University, Nanjing

210093, People’s Republic of China. [email protected] Key Laboratory of Pharmaceutical Biotechnology, School

of Life Sciences, Nanjing University, Nanjing 210093, People’s

Republic of China. [email protected] of Sciences, Nanjing Tech University, Nanjing 211816,

People’s Republic of China. [email protected]

Recognition of DNA depurination is of great importance for early

cancer detection [1]. Luminescent lanthanide complexes possess

some fascinating optical properties that have shown potential appli-

cations in biomedical researches [2]. In this study, a novel

terbium(III) complex (TbL) has been demonstrated to be capable of

recognizing purine nucleobases in DNA as a selective time-resolved

luminescence probe. The luminescence of TbL is enhanced remark-

ably upon reaction with oligonucleotides or natural DNA containing

purine bases in aqueous solution, while it is quenched dramatically as

depurination occurs to DNA. Mechanistic studies using the circular

dichroism and fluorescence spectroscopies revealed that the lumi-

nescence enhancement results from the preferential intercalations

between nitroimidazole moieties of TbL and purine bases of DNA,

which regulate the electron withdrawing effect of nitro groups via

hydrogen bonds and thereby affect the energy transfer from the ligand

to the metal center of the probe. This mechanism is also supported by

the molecular dynamics simulation results for the reaction. The dis-

tinct luminescence responses of TbL in the presence and absence of

purine bases in DNA make it a sensitive probe for DNA depurination

in physiological conditions.

Financial support by National Natural Science Foundation of

China is gratefully acknowledged.

References1. Dahlmann HA, Vaidyanathan VG, Sturla SJ (2009) Biochemistry

48:9347–9359

2. Bunzli JCG, Eliseeva SV (2013) Chem Sci 4:1939–1949


123

Date post:	07-Feb-2017
Category:	Documents
Upload:	vuongbao
View:	212 times
Download:	0 times

Oral presentations

Documents