title: Paramagnetic centers of carbon monoxide dehydrogenase from aceticlastic Methanosarcina barkeri.
abstract: Carbon monoxide dehydrogenase from Methanosarcina barkeri, purified to 95% homogeneity, contains 30 Fe, 2 Ni, 1 Zn, and 1 Cu (per alpha 2 beta 2 enzyme). Core extrusion experiments indicate 6 [4Fe-4S] clusters/tetramer, and electron paramagnetic resonance (epr) spectroscopy detects at least one of these clusters, in the reduced form, with apparent g values of 2.05, 1.94, and 1.90, and Em9.2-390 mV. A second epr signal, also seen in the reduced enzyme, has apparent g values of 2.005, 1.91, and 1.76, and Em9.2-35 mV. Two signals were seen in thionin-oxidized enzyme, one with a line shape suggestive of Cu(II), and the other resembling that of a [3Fe-4S] cluster. The enzymes nonphysiological substrate, CO, caused several spectral changes to the reduced enzyme, most notably a shift of the g = 1.76 feature to g = 1.73.
authors.affiliation: Exxon Research and Engineering Co., Annandale, New Jersey 08801.
authors.forename: J A
authors.initials: JA
authors.lastname: Krzycki
authors.forename: L E
authors.initials: LE
authors.lastname: Mortenson
authors.forename: R C
authors.initials: RC
authors.lastname: Prince
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000378:metabolism; D002248:Carbon Monoxide / Q000494:pharmacology*; D004578:Electron Spin Resonance Spectroscopy; D019605:Euryarchaeota / Q000201:enzymology*; D007506:Iron-Sulfur Proteins / Q000378:metabolism / Q000648:ultrastructure; D008667:Metalloproteins / Q000378:metabolism / Q000648:ultrastructure; D009097:Multienzyme Complexes; D010084:Oxidation-Reduction
chemical_list: D007506:Iron-Sulfur Proteins; D008667:Metalloproteins; D009097:Multienzyme Complexes; D002248:Carbon Monoxide; D000445:Aldehyde Oxidoreductases; C019823:carbon monoxide dehydrogenase