ENZYMIC FORMATION OF THIAMINE PYROPHOSPHATE IN PLANTS

Evidence was presented by paper chromatographic analysis on the occurrence of an enzyme capable of catalyzing a pyrophosphate transfer from ATP to thiamine in green leaves of various plants. The exclusive localization of the enzyme activity in the 105, 000×g supernatant (in a soluble form) was demonstrated by differential centrifugation of a cell homogenate in 0.25M sucrose. The enzyme was purified by column chromatography with DEAF-cellulose and by gel filtration with Sephadex G-150. The partially purified preparation, while contaminated with detectable activity of acid phosphatase, lost the ability of utilizing thiamine monophosphate as the substrate in place of thiamine. These findings lead to the conclusion that thiamine pyrophosphate is formed in green leaves of plants through a direct pyrophosphorylation of thiamine in the presence of ATP and Mg.