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We investigate the mechanism of multicenter redox enzymes by combining various kinetic techniques, including direct electrochemistry. By “direct electrochemistry”, we mean that the enzyme is adsorbed onto a rotating electrode which is immersed into a solution of the substrate, electron transfer between the enzyme and the electrode is direct, and the activity is simply monitored as a current. The data can be used to gain information about virtually every step in the mechanism. We work on various redox enzymes, particularly molybdoenzymes and hydrogenases, in collaboration with several biochemistry groups. We are interested in studying long distance electron transfer in multicenter redox enzymes, the mechanism at the active site of these enzymes, the oxygen sensibility of hydrogenases. We seek to understand the molecular basis of some of the global properties of redox enzymes: this includes catalytic bias, substrate specificity and resistance to chemical stress.

Our group is part of the FrenchBIC network. Funding is provided by the CNRS, the ANR, Aix-Marseille University, the région PACA and the City of Marseilles. We acknowledge support from the Pôle de compétitivité capenergies.

Projects

FeFe hydrogenases

FeFe-hydrogenases oxidize or produce H2 at an active site, the so-called H cluster, that is composed of a standard [4Fe4S] cluster covalently attached by a cysteine residue to a [Fe2 (CO)3 (CN)2 (dtma)] subsite (dtma = dithiomethylamine). We study the enzymes from Chlamydomonas reinhardtii (Collab. Hervé Bottin, CEA, Saclay) and Clostridium acetobutylicum (Collab. Isabelle Meynial-Salles, INSA /INRA/CNRS, Toulouse.). We also collaborate with theoretical chemists (Claudio Greco, Luca de Gioia, Universita degli Studi di Milano-Bicocca; Jochen Blumberger, UCL, London, UK). This research is funded by CNRS, AMU and the ANR (projects AlgoH2, CAFE, ECCHYMOSE). See a list of major results

NiFe hydrogenases

NiFe-hydrogenases oxidize or produce H2 at a dinuclear active site made of Ni and Fe. We study the enzymes from Desulfovibrio fructosovorans (Copllab. Myriam Brugna, BIP5, CNRS, Marseille) and Aquifex aeolicus (Collab. Marie Thérèse Giudici-Orticoni, BIP1, CNRS, Marseille). We also collaborate with theoretical chemists (Claudio Greco, Luca de Gioia, Universita degli Studi di Milano-Bicocca; Jochen Blumberger, UCL, London, UK), spectroscopists (Antonio de Lacey, ICP, CSCI, Madrid; Bruno Guigliarelli, Bénédicte Burlat, BIP7) and crystallographers (Juan Fontecilla-Camps, LCCP, CEA, Grenoble). This research is funded by CNRS, AMU, région PACA and the ANR (projects Hyliox and HEROS). See a list of major results

Aerobic catalysis with air-sensitive catalysts protected in hydrogel films

This collaboration with the group of Nicolas Plumeré in Bochum, Germany, is supported by an ANR/DFG program, SHIELDS

Carbon monoxide dehydrogenase

We study the carbon monoxide dehydrogenase from Desulfovibrio vulgaris. This enzymes reversibly transforms CO and CO2 using a NiFe4S active site. We are interested in understanding the maturation of the cofactor and the active site mechanism. For this we collaborate with theoretical chemists (Maurizio Bruschi, Luca de Gioia, Universita degli Studi di Milano-Bicocca; Jochen Blumberger, UCL, London, UK) and crystallographers (Catherine L. Drennan, MIT, Boston, USA). We also study the enzyme from Rhodospirulum rubrum in collaboration with Christine Cavazza (CEA, Grenoble). This research is funded by CNRS and AMU.

Mononuclear molybdoenzymes

We study several enzymes of the so-called “DMSO reductase family”. These enzymes share a similar mononuclear molybdenum cofactor (Moco), and are frequently involved in oxo transfer reactions: they catalyse the reduction of nitrate, DMSO, chlorate, arsenate or selenate, or the oxidation of arsenite or nitrite. In particular, we collaborate with the group of David Pignol (LBBC, CEA, Cadarache) for studying the nitrate reductase from Rhodobacter sphaeroides, with the group of Axel Magalon (LCB, CNRS, Marseille) for the formate dehydrogenase from E. coli, and Barbara Schoepp-Cottenet (BIP9, CNRS, Marseille) for studying arsenite oxidases and arseniate reductases. This research is funded by CNRS, AMU and the ANR (projects ERMOE, MC2


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