Zantema A, Vogel H J, Robillard G T
Eur J Biochem. 1979 Jun 1;96(3):453-63. doi: 10.1111/j.1432-1033.1979.tb13058.x.
A spin-labelled analogue of p-chloromercuribenzoate reacts specifically with glutamate dehydrogenase. The most marked change in the properties of the spin-labelled enzyme is a fivefold decrease in the rate of reduction of the coenzyme by L-glutamate and no change in the rate of oxidation by 2-oxoglutarate. The electron spin resonance spectrum is a sensitive probe for the conformational state of the enzyme. Spin-labelled glutamate dehydrogenase in the presence of saturating concentrations of NADPH and 2-oxoglutarate or L-glutamate shows a complete conformational change while in the presence of NADP+ and 2-oxoglutarate only half of the protomers have changed conformation. The conformational change upon addition of NADPH to the spin-labelled glutamate dehydrogenase in the presence of 2-oxoglutarate happens in a concerted way between 20 and 80% saturation with NADPH. One of the conformations is favoured by the activator ADP while the other is favoured by the inhibitor GTP.
对氯汞苯甲酸的自旋标记类似物与谷氨酸脱氢酶发生特异性反应。自旋标记酶性质最显著的变化是L-谷氨酸还原辅酶的速率降低了五倍，而2-氧代戊二酸氧化的速率没有变化。电子自旋共振光谱是酶构象状态的敏感探针。在饱和浓度的NADPH和2-氧代戊二酸或L-谷氨酸存在下，自旋标记的谷氨酸脱氢酶显示出完全的构象变化，而在NADP +和2-氧代戊二酸存在下，只有一半的原体发生了构象变化。在2-氧代戊二酸存在下，向自旋标记的谷氨酸脱氢酶中添加NADPH时，构象变化在NADPH饱和度为20%至80%之间以协同方式发生。其中一种构象受激活剂ADP青睐，而另一种受抑制剂GTP青睐。
