Electrochemical Measurements of the Kinetics of Inhibition of Two FeFe Hydrogenases by O2 Demonstrate That the Reaction Is Partly Reversible

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• 作者：Christophe Orain ; Laure Saujet ; Charles Gauquelin ; Philippe Soucaille ; Isabelle Meynial-Salles ; Carole Baffert ; Vincent Fourmond ; Herv茅 Bottin ; Christophe L茅ger
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：October 7, 2015
• 年：2015
• 卷：137
• 期：39
• 页码：12580-12587
• 全文大小：468K
• ISSN：1520-5126

文摘

The mechanism of reaction of FeFe hydrogenases with oxygen has been debated. It is complex, apparently very dependent on the details of the protein structure, and difficult to study using conventional kinetic techniques. Here we build on our recent work on the anaerobic inactivation of the enzyme [Fourmond et al. Nat. Chem. 2014, 4, 336鈥?42] to propose and apply a new method for studying this reaction. Using electrochemical measurements of the turnover rate of hydrogenase, we could resolve the first steps of the inhibition reaction and accurately determine their rates. We show that the two most studied FeFe hydrogenases, from Chlamydomonas reinhardtii and Clostridium acetobutylicum, react with O₂ according to the same mechanism, despite the fact that the former is much more O₂ sensitive than the latter. Unlike often assumed, both enzymes are reversibly inhibited by a short exposure to O₂. This will have to be considered to elucidate the mechanism of inhibition, before any prediction can be made regarding which mutations will improve oxygen resistance. We hope that the approach described herein will prove useful in this respect.