Electrochemical studies of CO 2 -reducing metalloenzymes

Only two enzymes are capable of directly reducing CO 2 : the CO dehydrogenase, which produces CO at a [NiFe 4 S 4 ] active site, and the formate dehydrogenase, which produces formate at a mononuclear W or Mo active site. Both metalloenzymes are very rapid, energy-efficient and specific in terms of product. They have been connected to electrodes with two different objectives. A series of studies used protein film electrochemistry to learn about different aspects of the mechanism of these enzymes (reactivity with substrates, inhibitors…). Another series focused on taking advantage of the catalytic performance of these enzymes to build biotechnological devices, from CO 2-reducing electrodes to full photochemical devices performing artificial photosynthesis. Here, we review all these works. Marta Meneghello obtained her Ph.D. in Chemistry from the University of Southampton (UK) in 2018, under the supervision of Prof P.N. Bartlett, working on the immobilization of redox enzymes at electrode surfaces. Since 2018, she is a postdoctoral researcher in the group of Christophe Leger and Vincent Fourmond at the CNRS of Marseille (France). Her current research focuses on kinetics studies of metalloenzymes, such as CO dehydrogenase and formate dehydrogenase, using electrochemical methods. Dr Christophe Léger obtained his Ph.D. from the University of Bordeaux and was a postdoc in the group of Fraser Armstrong from 1999 to 2002. He is "Directeur de Recherche" at CNRS. His interests lie in kinetic and mechanistic studies of complex metalloenzymes. Vincent Fourmond obtained his Ph.D. at the interface of physics and biology from Université Paris Diderot in 2007. He held postdoctoral positions first in the group of Christophe Léger in Marseille and then Vincent Artero in Grenoble, before coming back to Marseille as a permanent CNRS researcher in 2011. His research interests revolve around the use of kinetic techniques, principally protein film electrochemistry, to understand the mechanisms of metalloenzymes (hydrogenases, CO dehydrogenases, molybdenum enzymes), the development of methodological aspects of PFE, and the development and maintenance of the open source data analysis software QSoas [1] .