EFFECTS OF DEUTERIUM ON THE KINETICS OF BEEF-HEART MITOCHONDRIAL ATPASE
EFFECTS OF DEUTERIUM ON THE KINETICS OF BEEF-HEART MITOCHONDRIAL ATPASE
复制标题
DOI：
10.1016/0003-9861(84)90413-2
复制
发表时间：
1984-01-01
影响因子：
3.9
通讯作者：
SCHUSTER, SM
中科院分区：
文献类型：
--
作者：
URBAUER, JL;DORGAN, LJ;SCHUSTER, SM
在有或没有D2O的情况下，考察了f1催化ATP和ITP水解的稳态动力学作为温度的函数。得到了稳态动力学参数kcat和kcat/Km。对于ATP水解，在存在或不存在D2O的情况下，kcat/Km与温度无关，而ITP水解的kcat/Km在两种情况下都有所增加。在研究温度范围内，存在和不存在D2O时，kcat和kcat/Km的相对变化幅度与ATP和ITP水解的情况有很大不同。在ATP水解的kcat H2O/kcat D2O随温度的变化曲线中观察到正常的同位素效应，随着温度的升高，该效应先增加后趋于平稳。在ITP水解过程中，低温下的逆同位素效应转变为正常同位素效应，并随着温度的升高而急剧增加。讨论了反应机理中限速步骤的性质和位置。
The steady-state kinetics of F1-catalyzed ATP and ITP hydrolyses were examined in the presence or absence of D2O as a function of temperature. The steady-state kinetic parameters kcat and kcat/Km were obtained. For ATP hydrolysis, kcat/Km was independent of temperature in the presence or absence of D2O, while kcat/Km for ITP hydrolysis increased in both cases. The relative magnitudes of change of kcat and kcat/Km, in the presence and absence of D2O over the temperature range studied, were much different from the cases of ATP and ITP hydrolysis. A normal isotope effect was observed in plots of kcat H2O/kcat D2O vs. temperature for ATP hydrolysis, which increased then leveled off as temperature increased. An inverse isotope effect at low temperatures changed to a normal isotope effect and increased dramatically as temperature increased during ITP hydrolysis. The results are discussed in terms of the nature and location of the rate-limiting steps in the reaction mechanisms.