抄録
Quantitative determination of hydroxymethylpyrimidine diphosphate (OMP-PP) by enzymatic synthesis of thiamine from OMP-PP and thiazole monophosphate (Th-P) was investigated. Condensing enzyme, free from OMP-kinase, catalysing the condensation of OMP-PP and Th-P was obtained from bakers' yeast extract according to Iwashima et al. The thiamine formed after incubation with OMP-PP together with 10 μmole Th-P and condensing enzyme was determined by thiochrome assay after Takadiastase hydrolysis. The amount of the OMP-PP used was proportional to the thiamine estimated in the concentration range from 1 to 10 mμmole of OMP-PP, the reaction being almost complete within 10-30 minutes. The enzymatic formation of OMP-PP from OMP and ATP by the thiamine synthesizing enzyme prepared from bakers' yeast reached 30% of the OMP added when the ratio of OMP to ATP was 1 : 100.
