Pyridoxine is a precursor of the pyrimidine moiety of thiamin in Saccharomyces cerevisiae

Abstract

We studied the origin of the N-1 atom of the pyrimidine moiety of thiamin in a eucaryote, Saccharomyces cerevisiae. The competitive effects of 14N-compounds on the incorporation of 15N-NH4Cl into the pyrimidine moiety were examined. Amino acids, the bases of nucleic acids and glucosamine did not decrease 15N incorporation, but pyridoxine did. We conclude that the N-atom of pyridoxine is the origin of the N-1 atom of the pyrimidine of thiamin synthesized by S. cerevisiae. We also suggest that the N-atom of pyridoxine is derived from glutamine.