[22] Enzymatic formation of thiamine pyrophosphate in plants

Abstract

Publisher Summary This chapter reviews the enzymatic formation of thiamine pyrophosphate in plants. Thiamine pyrophosphokinase (EC 2.7.6.2) converts thiamine to thiamine pyrophosphate (TPP) through a direct transfer of pyrophosphate from adenosine triphosphate (ATP). The content of TPP formed during the enzyme reaction is manometrically determined by measuring the amount of the carbon dioxide evolved in the decarboxylation reaction in which the substrate, pyruvate, is transferred to acetaldehyde and carbon dioxide by pyruvate decarboxylase as a holoenzyme formed from the coenzyme produced, TPP, and added apoenzyme. The comparable relation between increasing concentrations of TPP and increasing activity of the decarboxylation—that is, the increasing amounts of evolved carbon dioxide—is accomplished under experimental conditions. The chapter describes the properties of the thiamine pyrophosphate obtained from plants.