Properties and interaction of heterologously expressed glutamate decarboxylase isoenzymes GAD65kDa and GAD67kDa from human brain with ginkgotoxin and its 5′-phosphate

被引：33

作者：

Buss, K ^{[1
]}

Drewke, C ^{[1
]}

Lohmann, S ^{[1
]}

Piwonska, A ^{[1
]}

Leistner, E ^{[1
]}

机构：

[1] Univ Bonn, Inst Pharmazeut Biol, D-53115 Bonn, Germany

来源：

JOURNAL OF MEDICINAL CHEMISTRY | 2001年 / 44卷 / 19期

关键词：

D O I：

10.1021/jm010868f

中图分类号：

R914 [药物化学];

学科分类号：

100701 ;

摘要：

Two isoforms of glutamate decarboxylase (GAD(65kDa) and GAD(67kDa)) from human brain, which had previously been overexpressed in Escherichia coli as fusion proteins containing a glutathione-S-transferase domain; were purified by affinity chromatography on glutathione Sepharose 4B. Both isoforms were also expressed in Saccharomyces cerevisiae. After modification of a HPLC based assay, the enzymes were characterized: with respect to their biochemical properties. Comparison of kinetic data, pH, and temperature optima as well as of the mode of interaction with pyridoxal phosphate as a cofactor revealed several significant differences between the two isoenzymes reflecting their somewhat different physiological and molecular features. Investigation of the influence of 4 ' -O-methylpyridoxine (ginkgotoxin) (1), a neurotoxin occurring in Ginkgo biloba L., on the different isoenzymes, indicates that the phosphorylated form of the toxin, 4 ' -O-methylpyridoxine-5 ' -phosphate (2), decreases GAD(65kDa) activity, although in unphysiologically high concentrations, whereas GAD(67kDa) activity seems to be hardly affected.

引用

页码：3166 / 3174

页数：9

共 52 条

[1] Occurrence of neurotoxic 4'-O-methylpyridoxine in Ginkgo biloba leaves, Ginkgo medications and Japanese Ginkgo food [J].