FEBS Letters | |
Activation of thiamine diphosphate in pyruvate decarboxylase from Zymomonas mobilis | |
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
【 预 览 】
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