OVERALL KINETIC MECHANISM OF 6-PHOSPHOGLUCONATE DEHYDROGENASE FROM CANDIDA-UTILIS

被引：35

作者：

BERDIS, AJ

COOK, PF

机构：

[1] TEXAS COLL OSTEOPATH MED,DEPT MICROBIOL & IMMUNOL,3500 CAMP BOWIE BLVD,FT WORTH,TX 76107

[2] TEXAS COLL OSTEOPATH MED,DEPT BIOCHEM & MOLEC BIOL,FT WORTH,TX 76107

来源：

BIOCHEMISTRY | 1993年 / 32卷 / 08期

关键词：

D O I：

10.1021/bi00059a021

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

A complete initial velocity study of the 6-phosphogluconate dehydrogenase from Candida utilis at pH 7 and 25-degrees-C in both reaction directions suggests a rapid equilibrium random kinetic mechanism with dead-end E:NADP:(ribulose 5-phosphate) and E:NADPH:(6-phosphogluconate) complexes. Like substrate-product (NADP/NADPH and 6-phosphogluconate/ribulose 5-phosphate) pairs are competitive whatever the concentration of the other substrates but noncompetitive versus the other substrates, e.g., NADPH exhibits noncompetitive inhibition versus 6-phosphogluconate. This trend also holds true for all dead-end analogs, e.g., ATP-ribose is competitive versus NADP and noncompetitive versus 6-phosphogluconate. A quantitative analysis of the kinetic inhibition constants supports the assignment of kinetic mechanism. The ratio of the maximum velocities in the oxidative decarboxylation and reductive carboxylation directions is 75.

引用

页码：2036 / 2040

页数：5

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