title: Direct electrochemical studies of hydrogenase and CO dehydrogenase.
abstract: The reduction potentials of two relatively high-molecular-mass enzymes were determined directly at an edge pyrolytic graphite electrode by using square-wave voltammetry. The equilibrium reduction potential versus standard hydrogen electrode was determined for Clostridium pasteurianum hydrogenase I (E'0 = -377 +/- 10 mV; molecular mass 60 kDa) and Rhodospirillum rubrum carbon monoxide dehydrogenase (E'0 = -418 +/- 7 mV; molecular mass 62 kDa). The reduction potential of each enzyme was pH-independent, and one electron was transferred per redox centre. The reduction potential was determined to be identical for the CO dehydrogenase, semi-apo-(CO dehydrogenase), and CO dehydrogenase with carbonyl sulphide (COS) or cyanide bound. The electron-transferring efficiency of CO dehydrogenase was affected by two inhibitors, COS and cyanide, as indicated by a diminished analytic current.
authors.affiliation: Department of Chemistry, University of Wisconsin-Milwaukee 53201.
authors.forename: E T
authors.initials: ET
authors.lastname: Smith
authors.forename: S A
authors.initials: SA
authors.lastname: Ensign
authors.forename: P W
authors.initials: PW
authors.lastname: Ludden
authors.forename: B A
authors.initials: BA
authors.lastname: Feinberg
mesh_terms: D000445:Aldehyde Oxidoreductases / Q000737:chemistry*; D002942:Circular Dichroism; D003013:Clostridium / Q000201:enzymology; D004563:Electrochemistry; D006864:Hydrogenase / Q000737:chemistry*; D009097:Multienzyme Complexes; D010084:Oxidation-Reduction; D012247:Rhodospirillum rubrum / Q000201:enzymology; D013056:Spectrophotometry, Ultraviolet
chemical_list: D009097:Multienzyme Complexes; D006864:Hydrogenase; D000445:Aldehyde Oxidoreductases; C019823:carbon monoxide dehydrogenase