Kinetic mechanism of pyruvate decarboxylase Evidence for a specific protonation of the enzymic intermediate

FEBS Letters

Ermer, Joachim¹  Hübner, Gerhard¹  Schellenberger, Alfred¹ 

[1] Martin-Luther-University Halle-Wittenberg, Institute of Biochemistry, Weinbergweg 16a, D-4020 Halle, Germany

关键词: Pyruvate docarboxylase mechanism;    Thiamine pyrophosphate;    Proton inventory;   

DOI  :  10.1016/0014-5793(92)80238-C

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Decarboxylation of pyruvate by pyruvate decarboxylase (EC 4.1.1.1) was performed in a reaction mixture containing 50% deuterium. The isolated product, acetaldehyde, was investigated directly by ¹H NMR and by mass spectrometry after conversion to the 2,4-dinitrophenyl hydrazone. The protium content of 56% at acetaldehyde Cl demonstrate a specific protonation of the corresponding intermediate by the enzyme. Proton inventory studies and enzyme modification indicate the 4′ amino group of the coenzyme, thiamine pyrophosphate, in an immonium structure being a possible proton donor. A ‘partially concerted’ mechanism is suggested for the reaction steps following the decarboxylation.

【 授权许可】

Unknown