A Novel Binuclear [CuSMo] Cluster at the Active Site of Carbon Monoxide Dehydrogenase: Characterization by X-ray Absorption Spectroscopy

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• 作者：Manuel Gnida ; Reinhold Ferner ; Lothar Gremer ; Ortwin Meyer ; and Wolfram Meyer-Klaucke
• 刊名：Biochemistry
• 出版年：2003
• 出版时间：January 14, 2003
• 年：2003
• 卷：42
• 期：1
• 页码：222 - 230
• 全文大小：221K
• 年卷期：v.42,no.1(January 14, 2003)
• ISSN：1520-4995

文摘

The structurally characterized molybdoenzyme carbon monoxide dehydrogenase (CODH)catalyzes the oxidation of CO to CO₂ in the aerobic bacterium Oligotropha carboxidovorans. The activesite of the enzyme was studied by Mo- and Cu-K-edge X-ray absorption spectroscopy. This revealeda bimetallic [Cu^ISMo^VI(=O)₂] cluster in oxidized CODH which was converted into a [Cu^ISMo^IV(=O)OH₍₂₎] cluster upon reduction. The Cu···Mo distance is 3.70 Å in the oxidized form and is increased to4.23 Å upon reduction. The bacteria contain CODH species with the complete and functional bimetalliccluster along with enzyme species deficient in Cu and/or bridging S. The latter are precursors in theposttranslational biosynthesis of the metal cluster. Cu-deficient CODH is the most prominent precursorand contains a [HSMo(=O)OH₍₂₎] cluster. Se-K-edge X-ray absorption spectroscopy demonstrates thatSe is coordinated by two C atoms at 1.94-1.95 Å distance. This is interpreted as a replacement of the Sin methionine residues. In contrast to a previous report [Dobbek, H., Gremer, L., Meyer, O., and Huber,R. (1999) Proc. Natl. Acad. Sci. U.S.A. 96, 8884-8889] Se was not identified in the active site of CODH.