精製アノイリナーゼIIの酵素化学的研究 : (II)反応速度と様式

概要

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The activity of thiaminase II was measured by the determination of remained thiamine in case of low concentration of the substrate and of formed oxymethylpyrimidine in case of high concentration of the substrate. The enzymatic reaction in low concentrations of the substrate (below 10^<-4> M/l) followed the first order reaction apparently, but not in fact the first order reaction. The cause of this phenomenon was considered to be brought by the inhibitory effect of the products on the reaction. And then, the reaction was investigated according to an equation induced from the Michaelis-Menten's equation by considering the inhibitory effect of the products. V_<max> was directly determined by the measurement of oxymethylpyrimidine and Mm was calculated from this value. V_<max>=1.05×10^<-9> M/min. protein N'1μg, Km=2.77×10^<-5>M/l (pH 7.0,37.5℃). The velocity of this reaction increased in proportion to OH ion concentration. From this result, it was supposed that the reaction might proceed as follows : [chemical formula]
日本ビタミン学会の論文