The oxidative half-reaction of old yellow enzyme - The role of tyrosine 196
The oxidative half-reaction of old yellow enzyme - The role of tyrosine 196
复制标题
DOI：
10.1074/jbc.273.49.32763
复制
发表时间：
1998-12-04
影响因子：
4.8
通讯作者：
Massey, V
中科院分区：
文献类型：
--
作者：
Kohli, RM;Massey, V
将老黄酶（OYE）中的酪氨酸196突变为苯丙氨酸，并对所得突变酶进行表征以评估残基的机械作用。残留物对配体结合和还原半反应的影响很小，但其与2-环己烯酮的氧化半反应急剧减慢近6个数量级。观察氧化半反应与一系列的基板，使我们能够提出一个模型描述的氧化半反应的机制。此外，减少与烯酮的反应性允许的方式，其中还原酶引发的氧化还原反应的底物通过观察与还原酶结合到基板的米氏复合物的表征。
Tyrosine 196 in Old Yellow Enzyme (OYE) was mutated to phenylalanine, and the resulting mutant enzyme was characterized to evaluate the mechanistic role of the residue. The residue demonstrates little effect on ligand binding and the reductive half-reaction, but a dramatic slowing by nearly 6 orders of magnitude of its oxidative half-reaction with 2-cyclohexenone. Observation of the oxidative half-reaction with a series of substrates allows us to propose a model describing the mechanism of the oxidative half-reaction. In addition, the curtailed reactivity with enones allows for characterization of the manner in which reduced enzyme primes the substrate for the redox reaction by observation of the Michaelis complex with reduced enzyme bound to substrate.