A kinetic and equilibrium analysis of the glutamic oxaloacetate transaminase mechanism.
A kinetic and equilibrium analysis of the glutamic oxaloacetate transaminase mechanism.
复制标题
谷氨酸草酰乙酸转氨酶机制的动力学和平衡分析。
DOI：
10.1016/s0021-9258(19)63406-x
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发表时间：
1962
期刊：
影响因子：
--
通讯作者：
J. Vavra
中科院分区：
文献类型：
--
作者：
S. Velick;J. Vavra
转氨酶的氨基载体功能是根据辅酶的性质和模型实验（1,2）来假设的，并通过观察吡哆醛和吡哆胺磷酸盐在粗聚谷氨酸草酰乙酸转氨酶的再活化中表现出相当的活性(3)以及在纯化酶的实验中通过直接分光光度法观察辅酶的相互转化(4)来建立酶促反应的氨基载体功能。该酶稳定且高活性，催化的反应可通过连续光学方法进行详细的动力学分析。此外，结合的辅酶表现出光谱变化，使其成为在底物水平酶浓度下进行的实验中发生事件的指标。因此，可以尝试用动力学推导出的机理和中间反应平衡，与在各种条件下通过检查结合的辅酶本身得到的结果相关联。谷氨酸草酰乙酸酶是大量实验上不易接近的转氨酶的机制原型，也是一般类型的基团转移酶的机制原型，它们完全通过二元酶底物复合物起作用。
The amino group carrier function of the coenzyme of transamination was postulated on the basis of coenzyme properties and model experiments(1, 2) and was established for the enzymatic reaction by the observation that pyridoxal and pyridoxamine phosphates exhibit equivalent activity in the reactivation of crude apoglutamate oxaloacetate transaminase (3) and by direct spectrophotometric observation of the coenzyme interconversion in experiments on the purified enzyme (4). The enzyme is stable and highly active and catalyzes a reaction that is susceptible to detailed kinetic analysis by continuous optical methods. Moreover, the bound coenzyme exhibits spectral changes that make it an indicator of events occurring in experiments carried out with substrate level concentrations of enzyme. It is therefore possible to attempt the correlation of mechanism and intermediary reaction equilibria, deduced kinetically, with results obtained by examination of the bound coenzyme itself under various conditions. The glutamate oxaloacetate enzyme is a mechanistic prototype for a large number of experimentally less accessible transaminases and also for the general class of group-transferring enzymes, which operate exclusively through binary enzyme substrate complexes.