Abstract
Thiamine phosphate pyrophosphorylase (EC 2.5.1.3) has been isolated from cell-free extracts of E. coli PT-R1 (pyrithiamine resistant mutant) and partially purified approximately 30-fold with regard to the specific activity. It was demonstrated that the enzyme catalyzes the synthesis of thiamine monophosphate from hydroxymethylpyrimidine pyrophosphate and hydroxyethylthiazole monophosphate in the same manner as the yeast enzyme. It was labile to heating and required Mg^<2+> for optimal activity. The optimal pH and temperature were estimated at 9.0 and 37℃ respectively. The reaction was inhibited by PCMB. The enzyme was also inhibited by ATP of which concentration showing 50% inhibition was 2.4×10^<-3>M.
