Kogan G L, Rozovskiĭ Ia M, Gvozdev V A
Biokhimiia. 1981 Mar;46(3):542-51.
Two isozymes of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) (G6PD) of Drosophila melanogaster encoded by allelic genes were purified 3000-fold by biospecific phosphocellulose chromatography, using NADP as the enzyme eluent. Electrophoretically fast isozyme A and slow isozyme B variants prove to contain identical subunits with molecular weight of 54000-55000. G6PD is shown to be a dimer. An antiserum directed to highly purified isozyme A does not inhibit the activity of both isozymes. The mutant forms of G6PD restoring the viability of flies without 6-phosphogluconate dehydrogenase show drastically increased Km values for NADP and/or glucose-6-phosphate. It was demonstrated for two mutations that a sharp (200-fold) magnification of Km value for the substrate followed by a considerable increase in the enzyme thermostability might not exert any essential influence on the Km value for NADP.
利用NADP作为酶洗脱剂，通过生物特异性磷酸纤维素色谱法，将由等位基因编码的黑腹果蝇葡萄糖-6-磷酸脱氢酶（EC 1.1.1.49）（G6PD）的两种同工酶纯化了3000倍。电泳快速同工酶A和慢速同工酶B变体经证明含有分子量为54000 - 55000的相同亚基。G6PD被证明是一种二聚体。针对高度纯化的同工酶A的抗血清不会抑制两种同工酶的活性。恢复无6 - 磷酸葡萄糖酸脱氢酶果蝇活力的G6PD突变形式显示其对NADP和/或葡萄糖-6-磷酸的Km值大幅增加。针对两个突变的研究表明，底物Km值急剧（200倍）放大，随后酶热稳定性显著提高，这可能不会对NADP的Km值产生任何实质性影响。
