Bautista J M, Garrido-Pertierra A, Soler G
Departamento de Bioquímica y Biologia Molecular y Genética, Universidad de Extremadura, Facultad de Veterinaria, Cáceres, Spain.
Biochim Biophys Acta. 1988 Dec 15;967(3):354-63. doi: 10.1016/0304-4165(88)90098-0.
The kinetic mechanism of the reaction catalyzed by glucose-6-phosphate dehydrogenase (EC 1.1.1.49) from Dicentrarchus labrax liver was examined using initial velocity studies, NADPH and glucosamine 6-phosphate inhibition and alternate coenzyme experiments. The results are consistent with a steady-state ordered sequential mechanism in which NADP+ binds first to the enzyme and NADPH is released last. Replots of NADPH inhibition show an uncommon parabolic pattern for this enzyme that has not been previously described. A kinetic model is proposed in agreement with our kinetic results and with previously published structural studies (Bautista et al. (1988) Biochem. Soc. Trans. 16, 903-904). The kinetic mechanism presented provides a possible explanation for the regulation of the enzyme by the [NADPH]/[NADP+] ratio.
利用初速度研究、NADPH和6-磷酸葡糖胺抑制以及替代辅酶实验，研究了来自欧洲鲈肝脏的6-磷酸葡萄糖脱氢酶（EC 1.1.1.49）催化反应的动力学机制。结果与稳态有序序列机制一致，其中NADP⁺首先与酶结合，NADPH最后释放。NADPH抑制的重绘图显示该酶呈现出一种此前未被描述过的不寻常抛物线模式。提出了一个动力学模型，该模型与我们的动力学结果以及先前发表的结构研究（Bautista等人，（1988年）《生物化学学会会报》16，903 - 904）一致。所提出的动力学机制为该酶受[NADPH]/[NADP⁺]比值调节提供了一种可能的解释。
