Vincent Fourmond

Speaker: Vincent Fourmond

Affiliation: CNRS institute, BIP (Bioénergétique et Ingénierie des Protéines), Marseille

Abstract: 

NiFe CO dehydrogenases (CODHs) are metalloenzymes that catalyze the reversible reduction of CO2 to CO at a NiFe4S4 active site. They are very fast, with rates of CO oxidation counting in tens of thousands per second, and reversible, able to perform the conversion with very little driving force. Only a handful of CODHs, with high sequence similarity, have been studied in depth so far. However, in spite of this high similarity, their properties were found to be widely different from one enzyme to the other, with Km values for CO oxidation ranging from 20 nM to 30 μM, and a large variability for the Km values for CO2, bimolecular rates of reaction with O2 spanning more than 2 orders of magnitude, and a large variation in their respective resistance to inactivation upon exposure to O2. We have investigated a number of different CODHs using a combination of Protein Film Electrochemistry, biochemical techniques and crystallography. We will present results discussing the origins of the exceptional resistance of the CODH from D. vulgaris to O2 linked to the formation of an alternative form of the active site, and studies of the reactivity of the CODHs with its substrate, with the demonstration that CO oxidation from CODH IV from C.hydrogenoformans is diffusion-limited and the study of the CO/CO2 access channel in newly purified CooS-type archeal CODHs.

About Vincent Fourmond:

Vincent is a researcher at the CNRS institute BIP (Bioénergétique et Ingénierie des Protéines) in Marseille, and a leading expert on the electrochemistry of metalloproteins, including CO2 reducing enzymes like CO dehydrogenases and formate dehydrogenases, and their kinetic characterization.