KINETIC STUDIES OF GLUTAMATE DEHYDROGENASE - REDUCTIVE AMINATION OF 2-OXOGLUTARATE
KINETIC STUDIES OF GLUTAMATE DEHYDROGENASE - REDUCTIVE AMINATION OF 2-OXOGLUTARATE
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DOI：
10.1042/bj1180409
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发表时间：
1970-01-01
影响因子：
4.1
通讯作者：
DALZIEL, K
中科院分区：
文献类型：
--
作者：
ENGEL, PC;DALZIEL, K
1.本文研究了在pH7.0和pH8.0条件下，以NADH和NADPH为辅酶的谷氨酸脱氢酶催化2-酮戊二酸还原胺化反应的动力学。底物和辅酶的浓度在很宽的范围内同时变化。Lineweaver-Burk图相对于每个底物和辅酶是线性的，除了与高浓度的2-酮戊二酸或辅酶抑制发生。在之前的逆反应动力学研究中，没有证据表明酶亚基之间存在负同向性相互作用。2.的初始速率的结果被证明是不一致的，这三个基板反应的六种可能的强制顺序机制，它的结论是，随机顺序机制是最有可能的。在此基础上，由初始速率参数计算了酶与底物的所有二元、三元和四元复合物的解离常数。3.结果进行了讨论，在较早的工人谁的结论是，该机制是强制命令类型。
1. Kinetic studies of the reductive amination of 2-oxoglutarate catalysed by glutamate dehydrogenase with NADH and NADPH as coenzyme were made at pH7.0 and pH 8.0. The concentrations of both substrates and coenzymes were simultaneously varied over wide ranges. Lineweaver–Burk plots with respect to each substrate and coenzyme were linear, except that with high concentrations of 2-oxoglutarate or coenzyme inhibition occurred. There was no evidence of the negative homotropic interactions between the enzyme subunits that were revealed in previous kinetic studies of the reverse reaction. 2. The initial-rate results are shown to be inconsistent with any of the six possible compulsory-order mechanisms for this three-substrate reaction, and it is concluded that a random-order mechanism is the most likely one. On the basis of this mechanism, the dissociation constants of all the binary, ternary and quaternary complexes of the enzyme and substrates are calculated from initial-rate parameters. 3. The results are discussed in relation to those of earlier workers who concluded that the mechanism is of the compulsory-order type.