title: Understanding and tuning the catalytic bias of hydrogenase.
abstract: When enzymes are optimized for biotechnological purposes, the goal often is to increase stability or catalytic efficiency. However, many enzymes reversibly convert their substrate and product, and if one is interested in catalysis in only one direction, it may be necessary to prevent the reverse reaction. In other cases, reversibility may be advantageous because only an enzyme that can operate in both directions can turnover at a high rate even under conditions of low thermodynamic driving force. Therefore, understanding the basic mechanisms of reversibility in complex enzymes should help the rational engineering of these proteins. Here, we focus on NiFe hydrogenase, an enzyme that catalyzes H(2) oxidation and production, and we elucidate the mechanism that governs the catalytic bias (the ratio of maximal rates in the two directions). Unexpectedly, we found that this bias is not mainly determined by redox properties of the active site, but rather by steps which occur on sites of the proteins that are remote from the active site. We evidence a novel strategy for tuning the catalytic bias of an oxidoreductase, which consists in modulating the rate of a step that is limiting only in one direction of the reaction, without modifying the properties of the active site.
authors.affiliation: Laboratoire de Bioénergétique et Ingénierie des Protéines, Institut de Microbiologie de la Méditerranée,  CNRS and Aix-Marseille Université , 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
authors.forename: Abbas
authors.initials: A
authors.lastname: Abou Hamdan
authors.forename: Sébastien
authors.initials: S
authors.lastname: Dementin
authors.forename: Pierre-Pol
authors.initials: PP
authors.lastname: Liebgott
authors.forename: Oscar
authors.initials: O
authors.lastname: Gutierrez-Sanz
authors.forename: Pierre
authors.initials: P
authors.lastname: Richaud
authors.forename: Antonio L
authors.initials: AL
authors.lastname: De Lacey
authors.forename: Marc
authors.initials: M
authors.lastname: Rousset
authors.forename: Patrick
authors.initials: P
authors.lastname: Bertrand
authors.forename: Laurent
authors.initials: L
authors.lastname: Cournac
authors.forename: Christophe
authors.initials: C
authors.lastname: Léger
mesh_terms: D020134:Catalytic Domain; D003901:Desulfovibrio / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D006864:Hydrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D009154:Mutation; D010084:Oxidation-Reduction; D013816:Thermodynamics
chemical_list: C043296:nickel-iron hydrogenase; D006864:Hydrogenase