Site-selective protonation of the one-electron reduced cofactor in [FeFe]-hydrogenase
| Autor: | Florian Wittkamp, Iuliia Baranova, Thomas Happe, Konstantin Laun, Jifu Duan, Sven T. Stripp, Leonie Kertess, Ulf-Peter Apfel, Moritz Senger |
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| Přispěvatelé: | Publica |
| Rok vydání: | 2021 |
| Předmět: |
Iron-Sulfur Proteins
Hydrogenase Electrons Context (language use) Protonation Photochemistry 010402 general chemistry 01 natural sciences [FeFe]-hydrogenases Cofactor Catalysis Inorganic Chemistry chemistry.chemical_compound H-2 oxidation biology H-2 evolution 010405 organic chemistry Biochemistry and Molecular Biology Active site 500 Naturwissenschaften und Mathematik::570 Biowissenschaften Biologie::570 Biowissenschaften Biologie Hydrogen-Ion Concentration 0104 chemical sciences chemistry Covalent bond biology.protein Protons Oxidation-Reduction Chlamydomonas reinhardtii Biokemi och molekylärbiologi Carbon monoxide |
| Zdroj: | Dalton Transactions |
| ISSN: | 1477-9226 |
| DOI: | 10.1039/d1dt00110h |
| Popis: | Hydrogenases are microbial redox enzymes that catalyze H2 oxidation and proton reduction (H2 evolution). While all hydrogenases show high oxidation activities, the majority of [FeFe]-hydrogenases are excellent H2 evolution catalysts as well. Their active site cofactor comprises a [4Fe-4S] cluster covalently linked to a diiron site equipped with carbon monoxide and cyanide ligands that facilitate catalysis at low overpotential. Distinct proton transfer pathways connect the active site niche with the solvent, resulting in a non-trivial dependence of hydrogen turnover and bulk pH. To analyze the catalytic mechanism of [FeFe]-hydrogenase, we employ in situ infrared spectroscopy and infrared spectro-electrochemistry. Titrating the pH under H2 oxidation or H2 evolution conditions reveals the influence of site-selective protonation on the equilibrium of reduced cofactor states. Governed by pKa differences across the active site niche and proton transfer pathways, we find that individual electrons are stabilized either at the [4Fe-4S] cluster (alkaline pH values) or at the diiron site (acidic pH values). This observation is discussed in the context of the natural pH dependence of hydrogen turnover as catalyzed by [FeFe]-hydrogenase. |
| Databáze: | OpenAIRE |
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