The origin of the carbon chain in the thiazole moiety of thiamine in Escherichia coli: incorporation of deuterated 1-deoxy-D-threo-2-pentulose

Non growing washed cells of Escherichia coli, derepressed for the biosynthesis of thiamine, have been incubated in the presence of glucose and either 1-deoxy-$\text{D}$-threo-2-pentulose $\text{1}$ or 1-déoxy-$\text{D}$-erythro-2-pentulose $\text{2}$ trideuterated on the methyl group. The incorporation of deuterium into the thiazole moiety of thiamine was measured by mass spectrometry. The label of the threo-compound was found in more than 40% of the thiazole biosynthesized in its presence; the label of the erythro-compound in less than 5%. Hence it is likely that the carbon chain of 1-deoxy-$\text{D}$-threo-2-pentulose is the precursor of the five carbons chain of the thiazole moiety of the thiamine molecule in E. coli.