Substrate and product inhibition initial rate kinetics of histone acetyltransferase.
Substrate and product inhibition initial rate kinetics of histone acetyltransferase.
复制标题
组蛋白乙酰转移酶的底物和产物抑制初始速率动力学。
作者：
J. Wiktorowicz;K. L. Campos;J. Bonner
组蛋白乙酰转移酶(EC2.3.1.48)反应的初始速度和产物抑制动力学表明，大鼠肝核酸酶是在快速平衡有序双反应机理下工作的。组蛋白首先加入到酶中，在本实验条件下，当乙酰辅酶A(CoA)浓度接近饱和时，Ka=0。乙酰辅酶A的Km为2.10+/-0.48微米。用乙酰赖氨酸抑制，酶-乙酰赖氨酸复合体的KiQ为1.96+/-0.30 mm。用辅酶A抑制产生3.19+/-0.48微米的三元络合物的Kip。这些结果表明，酶的活性相对独立于组蛋白的浓度，并且，由于酶只对乙酰辅酶A和辅酶A的浓度敏感，因此酶将倾向于将组蛋白维持在乙酰化状态。
Initial velocity and product inhibition kinetics of the histone acetyltransferase (EC 2.3.1.48) reaction indicate that the rat liver nuclear enzyme operates under a rapid equilibrium ordered bireactant mechanism. Histone adds first to the enzyme, and under the conditions of the experiment Ka = 0 as acetyl coenzyme A (CoA) concentration approaches saturating conditions. The Km for acetyl-CoA was 2.10 +/- 0.48 micrometer. Inhibition with acetyllysine resulted in a Kiq for the enzyme-acetyllysine complex of 1.96 +/- 0.30 mM. Inhibition with CoA yielded Kip for the ternary complex of 3.19 +/- 0.48 micrometer. These results indicate that the enzyme activity is comparatively independent of histone concentration, and, since the enzyme is sensitive only to acetyl-CoA and CoA concentrations, the enzyme will tend to maintain histones in the acetylated state.