Model for acetylene reduction by nitrogenase derived from density functional theory.

Johannes Kästner, Peter E Blöchl

Journal: Inorganic chemistry 2005;44(13):4568-75

PMID: 15962963

Full Text on American Chemical Society View on PubMed

Abstract

The catalytic cycle of acetylene reduction at the FeMo cofactor of nitrogenase has been investigated on the basis of density functional theory. C2H2 binds to the same site as N2, but it binds to a less reduced state of the cofactor. In a manner similar to that of N2 binding, one of the sulfur bridges opens during acetylene binding. The model explains the strong noncompetitive inhibition of N2 reduction by C2H2 and the weak competitive inhibition of C2H2 reduction by N2. Our proposed mechanism is consistent with experimentally observed stereoselectivity and the ability of C2H2 to suppress H2 production by nitrogenase.

Address: Institute for Theoretical Physics, Clausthal University of Technology, D-38678 Clausthal-Zellerfeld, Germany.

DOI: 10.1021/ic0500311

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MeSH Terms: Acetylene, Binding, Competitive, Catalytic Domain, Enzyme Inhibitors, Hydrogen, Models, Chemical, Molybdoferredoxin, Nitrogen, Nitrogenase, Oxidation-Reduction, Thermodynamics