Activation of thiamine diphosphate in pyruvate decarboxylase from Zymomonas mobilis

FEBS Letters

Tittmann, Kai²  Hübner, Gerhard²  Pohl, Martina¹  Mesch, Kathrin¹ 

[1] Institut für Enzymtechnologie, Forschungszentrum Jülich, D-52426 Jülich, Germany;Institut für Biochemie, Fachbereich Biochemie/Biotechnologie, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes Str. 3, D-06120 Halle, Germany

关键词: Thiamine diphosphate;    Pyruvate decarboxylase;    PDC;    pyruvate decarboxylase;    ThDP;    thiamine diphosphate;   

DOI  :  10.1016/S0014-5793(98)01594-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Replacement of tryptophan 392 located in the active site cavity of pyruvate decarboxylase (PDC; EC 4.1.1.1) from Zymomonas mobilis by methionine or glutamine yields enzymes with smaller catalytic constants of 8.5 s⁻¹ and 3.6 s⁻¹ at 4°C, compared to that of the wild-type enzyme (17 s⁻¹). The rate constants of the H/D exchange at the C2 of the coenzyme thiamine diphosphate have been determined to be 130 s⁻¹ for the wild-type enzyme, 56 s⁻¹ for the methionine and 30 s⁻¹ for the glutamine mutant, respectively. A group with a pK _a of about 5 has been identified to be essential for C2 deprotonation of the enzyme-bound thiamine diphosphate from the pH dependence of the H/D exchange.

【 授权许可】

Unknown