Bedino S
Ital J Biochem. 1976 Jul-Aug;25(4):304-19.
Inhibition of bovine liver glutamate dehydrogenase by pyridoxal-5'-phosphate was studied by measuring the full time course of the oxidation of NADPH. Progress curves were determined before and after incubation of the enzyme with PLP in the presence of saturating concentrations of alpha-ketoglutarate and ammonium ion, at pH 7.4 and 25 degrees C. The data were fitted to the integrated Michaelis-Menten equation and an inhibition model derived. According to the model, PLP inhibits the enzyme non-competitively, by reversible formation of the complexes E--PLP and E--PLP--NADPH; the oxidation of NADPH is also inhibited by NADP+. After incubation with PLP, the dissociation constants of E--NADPH and E--NADP+ (Km and Kp) show a very definite decrease, while the maximum rate of oxidation (Vm) is increased. The inhibition constants for PLP were also computed.
通过测定NADPH氧化的完整时间进程，研究了磷酸吡哆醛对牛肝谷氨酸脱氢酶的抑制作用。在pH 7.4和25℃条件下，于饱和浓度的α-酮戊二酸和铵离子存在时，将酶与PLP孵育前后测定反应进程曲线。将数据拟合到积分米氏方程并推导抑制模型。根据该模型，PLP通过可逆形成复合物E--PLP和E--PLP--NADPH对酶产生非竞争性抑制作用；NADP+也抑制NADPH的氧化。与PLP孵育后，E--NADPH和E--NADP+的解离常数（Km和Kp）呈现非常明显的下降，而最大氧化速率（Vm）增加。还计算了PLP的抑制常数。
