title: Electron transfer between the hydrogenase from Desulfovibrio vulgaris (Hildenborough) and viologens. 1. Investigations by cyclic voltammetry.
abstract: The electron transfer kinetics between the hydrogenase from Desulvovibrio vulgaris (strain Hildenborough) and three different viologen mediators has been investigated by cyclic voltammetry. The mediators methyl viologen, di(n-aminopropyl) viologen and propyl viologen sulfonate differ in redox potential and in net charge. Dependent on the pH both the one- and two-electron-reduced forms or only the two-electron-reduced form of the viologens are effective in electron exchange with hydrogenase. Calculations of the second-order rate constant k for the reaction between reduced viologen and hydrogenase are based on the theory of the simplest electrocatalytic mechanism. Values for k are in the range of 10(6)-10(7) M-1 s-1 and increase in the direction propyl viologen sulfonate----methyl viologen----di(n-aminopropyl) viologen. An explanation is based on electrostatic interactions. It is proposed that the electron transfer reaction is the rate-determining step in the catalytic mechanism.
authors.affiliation: Laboratory of Biochemistry, Agricultural University, Wageningen, The Netherlands.
authors.forename: J C
authors.initials: JC
authors.lastname: Hoogvliet
authors.forename: L C
authors.initials: LC
authors.lastname: Lievense
authors.forename: C
authors.initials: C
authors.lastname: van Dijk
authors.forename: C
authors.initials: C
authors.lastname: Veeger
mesh_terms: D002384:Catalysis; D003901:Desulfovibrio / Q000201:enzymology*; D004563:Electrochemistry; D004579:Electron Transport; D004735:Energy Transfer; D006863:Hydrogen-Ion Concentration; D006864:Hydrogenase / Q000378:metabolism*; D007700:Kinetics; D010084:Oxidation-Reduction; D011726:Pyridinium Compounds / Q000378:metabolism*; D014755:Viologens / Q000378:metabolism*
chemical_list: D011726:Pyridinium Compounds; D014755:Viologens; D006864:Hydrogenase