人红细胞葡萄糖-6-磷酸脱氢酶二聚体的动力学

Kinetics of human erythrocyte glucose-6-phosphate dehydrogenase dimers.

作者信息

Birke S, Kim H W, Periclou A, Schorsch B, Grouse D, Craney C

机构信息

Department of Chemistry Occidental College, Los Angeles, CA 90041.

出版信息

Biochim Biophys Acta. 1989 Dec 21;999(3):243-7. doi: 10.1016/0167-4838(89)90004-6.

DOI:10.1016/0167-4838(89)90004-6

PMID:2605261

Abstract

The steady-state kinetics of human erythrocyte glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP+ 1-oxidoreductase, EC 1.1.1.49) dimers were studied by initial rate measurement. These experiments gave intersecting double-reciprocal plots suggesting a ternary complex mechanism with a Km for NADP and glucose 6-phosphate of 11 microM and 43 microM, respectively. These studies were combined with rate measurements in the presence of one product (NADPH), dead-end inhibitors, as well as alternative substrates. The inhibition by NADPH was found to be competitive with respect to both substrates. Alternate substrates experiments gave linear double-reciprocal plots over a wide range of substrate concentrations. The results suggest that the dimeric enzyme follows either a random or a Theorell-Chance mechanism.

摘要

通过初速率测定研究了人红细胞葡萄糖-6-磷酸脱氢酶（D-葡萄糖-6-磷酸：NADP + 1-氧化还原酶，EC 1.1.1.49）二聚体的稳态动力学。这些实验给出了相交的双倒数图，表明存在三元复合物机制，其中NADP和葡萄糖6-磷酸的Km分别为11 microM和43 microM。这些研究与在一种产物（NADPH）、终产物抑制剂以及替代底物存在下的速率测量相结合。发现NADPH对两种底物的抑制作用均为竞争性抑制。替代底物实验在很宽的底物浓度范围内给出了线性双倒数图。结果表明，二聚体酶遵循随机机制或Theorell-Chance机制。