title: Pyrococcus furiosus glyceraldehyde 3-phosphate oxidoreductase has comparable W(6+/5+) and W(5+/4+) reduction potentials and unusual [4Fe-4S] EPR properties.
abstract: Pyrococcus furiosus glyceraldehyde 3-phosphate oxidoreductase has been characterized using EPR-monitored redox titrations. Two different W signals were found. W(1)(5+) is an intermediate species in the catalytic cycle, with the midpoint potentials E(m)(W(6+/5+))=-507 mV and E(m)(W(5+/4+))=-491 mV. W(2)(5+) represents an inactivated species with E(m)(W(6+/5+))=-329 mV. The cubane cluster exhibits both S=3/2 and S=1/2 signals with the same midpoint potential: E(m)([4Fe-4S](2+/1+))=-335 mV. The S=1/2 EPR signal is unusual with all g values below 2.0. The titration results combined with catalytic voltammetry data are consistent with electron transfer from glyceraldehyde 3-phosphate first to the tungsten center, then to the cubane cluster and finally to the ferredoxin.
authors.affiliation: Wageningen University, Department of Biomolecular Sciences, Bioinorganic Chemistry Group, Dreijenlaan 3, 6703 HA, Wageningen, The Netherlands. peter.leonhagedoorn@epr.bc.wau.nl
authors.forename: P L
authors.initials: PL
authors.lastname: Hagedoorn
authors.forename: J R
authors.initials: JR
authors.lastname: Freije
authors.forename: W R
authors.initials: WR
authors.lastname: Hagen
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D005986:Glyceraldehyde 3-Phosphate / Q000378:metabolism; D010084:Oxidation-Reduction; D020027:Pyrococcus furiosus / Q000201:enzymology* / Q000378:metabolism; D017186:Titrimetry; D014414:Tungsten / Q000378:metabolism
chemical_list: D005986:Glyceraldehyde 3-Phosphate; D000429:Alcohol Oxidoreductases; C052705:L-glyceraldehyde 3-phosphate-NADPH-dependent oxidoreductase; D014414:Tungsten