KINETIC STUDIES ON THE ACTION OF GLUCOSE DE-HYDROGENASE:III. COMPETITIVE INTERACTION BETWEEN TWO SUBSTRATES IN THEIR REACTION WITH THE ENZYME MOLECULE

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1. Using the glucose dehydrogenase isolated from Aspergillus oryzae the mutual actions between two oxidizable substrates or between oxidizable and non-oxidizable substances were investigated by kinetic methods.<br> 2. Competitive actions were found to take place between D-glucose, D-xylose, D-galactose, D-mannose and D-arabinose, among which only D-arabinose has been shown to be innert against the action of the enzyme. The mutual effects expected to occur between two substrates were calculated from the Michaeli s constants and the maximum velo-cities of oxidation (to be observed in the presence of sufficiently -high concentrations of substrate) which had been determined separately for each substrate, and the calculated values were shown to be -in good agreement with the observed ones.<br> 3. 6-Phospho-D-glucose which has been shown to be dehydrogenated -with a fairly small Michaelis constant-by the enzyme preparation used, did not interfere with the oxidation of D-glucose by the enzyme. It was, therefore, suspected that the oxidation of this substance was caused by some specific enzyme that was present as an impurity in the preparation of the glucose dehydrase.<br><br> The author wishes to express his thanks to Prof. H. Tamiya for his helpful interest and advice in this research.

Journal

  • J Biochem (Tokyo)

    J Biochem (Tokyo) 39 (3), 311-320, 1952

    The Japanese Biochemical Society

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