Abstract
Studies on biosynthesis of thiamine by Sacch. cerevisiae were carried out and the following results were obtained. (1) It was recognized that 2-methyl-4-amino-5-hydroxymethyl-pyrimidine or its compounds, 2-methyl-4-amino-5-aminomethyl-pyrimidine and 2-methyl-4-amino-5-formaminomethyl-pyrimidine, were good source of thiamine synthesis among various kinds of pyrimidines in existence of thiazole moiety when Sacch. cerevisiae was cultured in Reader's medium. (2) An ability of thiamine synthesis from 2-methyl-4-amino-5-hydroxymethylpyrimidine and thiazole by the washed cells of Sacch.cerevisiae which were cultured in the medium without material for synthesis of thiamine was evidently proved. The optimum pH of the synthesis was about 7.0-7.5. (3) It was also proved that the cell free extract of Sacch. cerevisiae had a complete enzyme system of the thiamine synthesis from pyrimidine and thiazole. Moreover, it was recognized that the fraction of 65% ammonium sulfate of the extract easily synthesed thiazole under the existence of ATP and Mg.
