Abstract
The origin of methyl group (C-8) attached to C-2 of the pyrimidine moiety in procaryotes, and the precursor of the C-2 and C-8 atoms in eucaryotes on thiamin biosynthesis have not yet been established. Johnson et al. and Tomlinson had reported the incorporation of acetate into the pyrimidine moiety in Saccharomyces cerevisiae and Bacillus subtilis. We investigated the incorporation of acetate into the pyrimidine moiety in Esherichia coli and S. cerevisiae. The results obtained showed that acetate neither incorporated into the pyrimidine nor the thiazole moiety. We furthermore studied the incorporation of glycerol, pyruvate and alanine into the thiazole moiety in E. coli and S. cerevisiac. Glycerol and pyruvate but not alanine were incorporated into the thiazole moiety in E. coli. However in S. cerevisiae, incorporation of alanine that had been reported by Johnson and others was not observed.
