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Publication Abstract from PubMed

Hydrogenases are H2 converting enzymes that harbor catalytic cofactors in which iron (Fe) ions are coordinated by biologically unusual carbon monoxide (CO) and cyanide (CN-) ligands. Extrinsic CO and CN-, however, inhibit hydrogenases. The mechanism by which CN- binds to [FeFe]-hydrogenases is not known. Here, we obtained crystal structures of the CN--treated [FeFe]-hydrogenase CpI from Clostridium pasteurianum. The high resolution of 1.39 A allowed us to distinguish intrinsic CN- and CO ligands and to show that extrinsic CN- binds to the open coordination site of the cofactor where CO is known to bind. In contrast to other inhibitors, CN- treated crystals show conformational changes of conserved residues within the proton transfer pathway which could allow a direct proton transfer between E279 and S319. This configuration has been proposed to be vital for efficient proton transfer, but has never been observed structurally.

Cyanide Binding to [FeFe]-Hydrogenase Stabilizes the Alternative Configuration of the Proton Transfer Pathway.,Duan J, Hemschemeier A, Burr DJ, Stripp ST, Hofmann E, Happe T Angew Chem Int Ed Engl. 2022 Dec 4. doi: 10.1002/anie.202216903. PMID:36464641^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.