Quantum Refinement of [FeFe] Hydrogenase Indicates a Dithiomethylamine Ligand

摘要

Hydrogenases play an important role in the metabolism of manynmicroorganisms by performing reversible oxidation of hydrogen:nH2 a 2H+ + 2e-.1 Three classes are known, depending on thenmetal content of the active site: [NiFe], [FeFe], and [Fe] hydrogenases.nThe [FeFe] hydrogenases have been extensively studiednusing experimental and theoretical methods.1–3 Crystal structuresnare available for [FeFe] hydrogenases from two bacteria.4,5 Thenactive site consists of a ferredoxin-like [4Fe4S] cluster connectednvia a Cys residue to a binuclear Fe2 cluster, where each Fe ion hasnone CO and one CN- ligand. In addition, there are three bridgingngroups, another CO, and a dithiolate ligand (Figure 1). The Fe ionndistal to the [4Fe4S] cluster (Fed) has a vacant coordination sitenthat is believed to be the reactive center. In some oxidized structures,na water molecule is found in this site.