Abstract
Phenylthiazinothiamine (PTT) was shown to have no inhibition of thiamine biosynthesis from its pyrimidine and thiazole moieties : 2-methyl-4-amino-5-hydroxymethylpyrimidine (OMP) and 4-methyl-5-(β-hydroxy) ethylthiazole (MHT), by Saccharomyces cerevisiae. Biosynthesis of thiamine by yeast cells with PTT even in the broth containing 50μg of thiamine was proved to be completed without absorption of the thiamine from the broth. The standard assay method suggested by the authours is as follows. Cells of Sacch. cerevisiae cultured in Atkin's medium (16hrs. at 30℃) were harvested and suspended in 15 ml of Reader's medium (O.D. 1.0). After addition of MHT (1μmole), PTT (1 μmole) and OMP (0.01〜0.1 μmole) or sample to the suspension, it was incubated for 3 hrs. at 30℃ and the thiamine content in the centrifuged yeast cells was determined by thiochrome method.
