Abstract
The enzymatic activity concerning the thiamine synthesis in bakers' yeast extract was demonstrated by incubating the extract with 2-methyl-4-amino-5-hydroxymethylpyrimidine (OMP), 4-methyl-5β-hydroxyethylthiazole (Th), ATP and Mg^<2+>. The activity was lost by heating the extract at 55℃ for 2 minutes. On the contrary, the activity of thiamine synthesis detected by incubating the extract with OMP-pyrophosphate and Th-phosphate in the absence of ATP or with OMP-pyrophosphate, Th, ATP and Mg^<2+> remained unchanged under such a condition. These findings suggest the removal of OMP-kinase by heating. The existence of the enzymatic activity concerning thiamine synthesis in the extract and in the suspension of the mitochondria obtained from a rat liver was investigated according to the preparation method of the enzyme system from bakers' yeast. No activity was found in any step of the synthesis of the vitamin. Furthermore the administration of both OMP-pyrophosphate and Th-phosphate failed to show any effects on thiamine-deficient albino rats.
