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Humboldt-Universitaet zu Berlin - Structural Biology / Biochemistry

Humboldt-Universitaet zu Berlin | Department of Biology | Structural Biology / Biochemistry | Publications | Crystal structure and mechanism of CO-Dehydrogenase, a molybdo iron-sulfur flavoprotein containing S-selanylcysteine

Holger Dobbek, Lothar Gremer, Ortwin Meyer, and Robert Huber (1999)

Crystal structure and mechanism of CO-Dehydrogenase, a molybdo iron-sulfur flavoprotein containing S-selanylcysteine

Proceedings of the National Academy of Sciences US, 96(16):8884–8889.

CO dehydrogenase from the aerobic bacterium Oligotropha carboxidovorans catalyzes the oxidation of CO with H(2)O, yielding CO(2), two electrons, and two H(+). Its crystal structure in the air-oxidized form has been determined to 2.2 A. The active site of the enzyme, which contains molybdenum with three oxygen ligands, molybdopterin-cytosine dinucleotide and S-selanylcysteine, delivers the electrons to an intramolecular electron transport chain composed of two types of [2Fe-2S] clusters and flavin-adenine dinucleotide. CO dehydrogenase is composed of an 88.7-kDa molybdoprotein (L), a 30. 2-kDa flavoprotein (M), and a 17.8-kDa iron-sulfur protein (S). It is organized as a dimer of LMS heterotrimers and resembles xanthine dehydrogenase/oxidase in many, but not all, aspects. A mechanism based on a structure with the bound suicide-substrate cyanide is suggested and displays the necessity of S-selanylcysteine for the catalyzed reaction.