title: Electron paramagnetic resonance (EPR) studies on hydrogenase-1 (HYD1) purified from a mutant strain (AP6) of Escherichia coli enhanced in HYD1.
abstract: Hydrogenase-1 (HYD1), overexpressed by twofold, has been purified to homogeneity and to a high specific activity from a mutant strain (AP6) of Escherichia coli which lacks hydrogenase-2. Plasma emission spectroscopy indicated that 0.93 atom of nickel and 11.4 iron atoms were present in HYD1. EPR studies on the as isolated HYD1 detected a complex 3Fe-4S signal and a Ni(III) species. Reduction with hydrogen gas caused disappearance of both the 3Fe-4S cluster and initial Ni(III) signals. At the same time the EPR signature (small g = 2.19 signal) of the activated hydrogenase appeared. The detection of a 4Fe-4S cluster signal was noted. Reduction of HYD1 with sodium dithionite caused all nickel signals to disappear. The 4Fe-4S complex intensity was slightly increased. The EPR responses in the three oxidation-reduction states are consistent with other known (NiFe)-hydrogenases.
authors.affiliation: Department of Biochemistry & Molecular Biology, University of Georgia, Athens 30602, USA. dervar@bchiris.biochem.uga.edu
authors.forename: M E
authors.initials: ME
authors.lastname: DerVartanian
authors.forename: N K
authors.initials: NK
authors.lastname: Menon
authors.forename: A E
authors.initials: AE
authors.lastname: Przybyla
authors.forename: H D
authors.initials: HD
authors.lastname: Peck
authors.forename: D V
authors.initials: DV
authors.lastname: DerVartanian
mesh_terms: D004227:Dithionite / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D006864:Hydrogenase / Q000737:chemistry* / Q000302:isolation & purification; D009154:Mutation; D010084:Oxidation-Reduction
chemical_list: D004227:Dithionite; D006864:Hydrogenase