Autocatalytic Oscillations in the Early Phase of the Photoreduced Methyl Viologen-initiated Fast Kinetic Reaction of Hydrogenase

The kinetic characteristics of the hydrogen uptake reaction of hydrogenase, obtained by conventional activity measurements, led to the proposal of an autocatalytic reaction step in the hydrogenase cycle or during the activation process. The autocatalytic behavior of an enzyme reaction may result in...

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Bibliographic Details
Published in:The Journal of biological chemistry 2003-06, Vol.278 (23), p.20624-20627
Main Authors: Bagyinka, Csaba, Ösz, Judit, Száraz, Sándor
Format: Article
Language:English
Subjects:
Catalysis
Enzyme Activation
Herbicides - pharmacology
Hydrogen - metabolism
Hydrogenase - metabolism
Lasers
Nitrogen
Oxidation-Reduction
Paraquat - pharmacology
Periodicity
Photochemistry
Thiocapsa roseopersicina - enzymology
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Summary:The kinetic characteristics of the hydrogen uptake reaction of hydrogenase, obtained by conventional activity measurements, led to the proposal of an autocatalytic reaction step in the hydrogenase cycle or during the activation process. The autocatalytic behavior of an enzyme reaction may result in oscillating concentrations of enzyme intermediates and/or products contributing to the autocatalytic step. This behavior has been investigated in the early phase of the hydrogenase-methyl viologen reaction. To measure fast hydrogenase kinetics, flash-reduced methyl viologen has been used as a light-induced trigger in transient kinetic phenomena associated with intermolecular electron transfer to hydrogenase. Here we report fast kinetic measurements of the hydrogenase-methyl viologen reaction by use of the excimer laser flash-reduced redox dye. The results are evaluated on the assumption of an autocatalytic reaction in the hydrogenase kinetic cycle. The kinetic constants of the autocatalytic reaction, i.e. the methyl viologen binding to and release from hydrogenase, were determined, and limits of the kinetic constants relating to the intramolecular (intraenzyme) reactions were set.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M300623200