抄録
Phenylalanine and histidine, out of several amino acids tested by the addition to the growth medium of Escherichia coli, showed stimulatory effects on thiamine production by the cells. In order to know the mechanism of phenylalanine action, it was compared with the adenine effect in which adenine added to the growth medium caused a decrease in thiamine production of E. coli accompanying with the increase of thiamine synthesizing activity from hydroxymethylpyrimidine and thiazole. Phenylalanine had also a similar elevating effect on thiamine synthesizing activity from hydroxymethylpyrimidine and thiazole in spite of the increase in cellular thiamine contents. The phenylalanine effect could be abolished by a simultaneous thiazole addition at a physiological concentration for the organism in contrast with the adenine effect, which was arrested by hydroxymethylpyrimidine addition. The phenylalanine effect is supposed to be concerned with the synthesis of thiazole moiety of thiamine. The regulation of thiamine biosynthesis in E. coli was also discussed.
