Glutamate synthase: on the kinetic mechanism of the enzyme from Escherichia coli W.
Glutamate synthase: on the kinetic mechanism of the enzyme from Escherichia coli W.
复制标题
谷氨酸合酶：大肠杆菌 W 酶的动力学机制。
DOI：
10.1021/bi00618a011
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发表时间：
1978
期刊：
影响因子：
2.9
通讯作者：
W. Orme
中科院分区：
文献类型：
--
作者：
A. Rendina;W. Orme
Alan R.作者声明：William H. Orme-Johnson* 摘要：在pH7.5，25 ℃条件下，研究了谷氨酸合成酶催化L-谷氨酰胺和NADPH还原胺化-酮戊二酸（-KG）的动力学机理。对最大速度-pH值曲线的研究表明，在正向方向上的p/Us分别为6.7和8.3。2 '-腺苷酸、草酰甘氨酸、O-氨基甲酰丝氨酸和L-甲硫氨酸砜的初始速度、产物和死端抑制模式与两个位点的乒乓单-单-双-双机制一致。在这种机制中，这两个网站可能是连接的黄素和Fe-S中心作为电子载体。以a-KG、L-谷氨酰胺和L-谷氨酸（l-G_（1u））为底物的双-双部分反应，利用快速平衡的随机双-双机制，
Alan R. Rendina and William H. Orme-Johnson* abstract: The kinetic mechanism for the reductive amination of-ketoglutarate (-KG) by L-glutamine and NADPH catalyzed by glutamate synthase was determined at pH 7.5, 25 C. Examination of the maximum velocity-pH profile in the thermodynamicforward direction gave p/Us of 6.7 and 8.3. The initial velocity, product, and dead-end inhibition patterns for 2'-adenylic acid, oxalylglycine, O-carbamoylserine, and L-methionine sulfone are consistent with a two-site ping-pong uni-uni bi-bi mechanism. In this mechanism the two sites are presumably linked by flavins and Fe-S centers which function as electron carriers. The bi-bi partial reaction, in which a-KG, L-glutamine, and L-glutamate (l-G1u) are the substrates, is proposed to utilize a rapid equilibrium random bi-bi mecha-