title: Infrared studies of carbon monoxide binding to carbon monoxide dehydrogenase/acetyl-CoA synthase from Moorella thermoacetica.
abstract: Carbon monoxide dehydrogenase/acetyl-CoA synthase (CODH/ACS) is a bifunctional enzyme that catalyzes the reversible reduction of carbon dioxide into carbon monoxide and the coupled synthesis of acetyl-CoA from the carbon monoxide produced. Exposure of CODH/ACS from Moorella thermoacetica to carbon monoxide gives rise to several infrared bands in the 2100-1900 cm(-1) spectral region that are attributed to the formation of metal-coordinated carbon monoxide species. Infrared bands attributable to M-CO are not detected in the as-isolated enzyme, suggesting that the enzyme does not contain intrinsic metal-coordinated CO ligands. A band detected at 1996 cm(-1) in the CO-flushed enzyme is assigned as arising from CO binding to a metal center in cluster A of the ACS subunit. The frequency of this band is most consistent with it arising from a terminally coordinated Ni(I) carbonyl. Multiple infrared bands at 2078, 2044, 1970, 1959, and 1901 cm(-1) are attributed to CO binding at cluster C of the CODH subunit. All infrared bands attributed to metal carbonyls decay in a time-dependent fashion as CO(2) appears in the solution. These observations are consistent with the enzyme-catalyzed oxidation of carbon monoxide until it is completely depleted from solution during the course of the experiments.
authors.affiliation: Department of Chemistry, Buffalo State, State University of New York, Buffalo, New York 14222, USA.
authors.forename: Jingyi
authors.initials: J
authors.lastname: Chen
authors.forename: Shan
authors.initials: S
authors.lastname: Huang
authors.forename: Javier
authors.initials: J
authors.lastname: Seravalli
authors.forename: Howard
authors.initials: H
authors.lastname: Gutzman
authors.forename: Derrick J
authors.initials: DJ
authors.lastname: Swartz
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Ragsdale
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Bagley
mesh_terms: D000106:Acetate-CoA Ligase / Q000737:chemistry*; D000445:Aldehyde Oxidoreductases / Q000737:chemistry*; D001665:Binding Sites; D002248:Carbon Monoxide / Q000737:chemistry*; D003013:Clostridium / Q000201:enzymology; D004578:Electron Spin Resonance Spectroscopy; D009097:Multienzyme Complexes / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
chemical_list: D009097:Multienzyme Complexes; D002248:Carbon Monoxide; D000445:Aldehyde Oxidoreductases; C019823:carbon monoxide dehydrogenase; D000106:Acetate-CoA Ligase