Abstract
Formate is incorporated into the C-2 of the pyrimidine moiety of thiamin in Escherichia coli under aerobic conditions. However, the incorporation of formate into the pyrimidine was decreased under anaerobic conditions. Although the incorporation of [^<13>C] formate into pyrimidine was decreased under static and anaerobic conditions, the incorporation was not inhibited by pantothenate or aspartate. These results suggest that another biosynthetic route for the pyrimidine is induced under anaerobic conditions in E. coli. On the other hand, the nitrogen atom of L-[^<15>N]tyrosine was incorporated into the thiazole moiety of thiamin under aerobic and anaerobic conditions. The biosynthetic route of the thiazole moiety was not changed by O_2 concentration.
