Clostridium sporogenesのThiaminaseの研究 : (III)精製Thiaminase IによるThiamineの合成

概要

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It is well known that thiaminase I catalizes the transfer of the pyrimidinyl group from various onium compounds containing (4-amino-2-methyl-5-pyrimidinyl) methyl group to 4-methyl-5-(β-hydroxyethyl) thiazole (Th) to form thiamine. Some properties of the thiamine synthesis with N-pyrimidinyl pyridoxinium-3-phenolate (Pm-PIN) and Th by the purified thiaminase I from Cl. sporogenes ATCC 8075 were investigated. The optimal pH of the reaction was 6.0 and the optimal temperature was 20℃. The enzyme was completely destroyed by heating for 10 min at 70℃. Thiamine synthesizing ability of the enzyme was accelerated with sulfhydryl compounds and inhibited with SH reagents, as in the case of the thiamine decomposing reaction. The inhibition by p-chloromercuribenzoate was completely restored by dithiothreitol. The effects of metal ions on the thiamine synthesis was the same as that on the thiamine decomposition. The K_m values in the thiamine synthesis at 20℃ (pH 6.0) in the presence of dithiothreitol were 3.3×10^<-5>M for Pm-PIN, 3.0×10^<-5>M for N-pyrimidinyl pyridinium bromide hydrobromide, and 1.11×10^<-4>M for Th.
日本ビタミン学会の論文
1975-04-25