Ebel R E, Lardy H A
J Biol Chem. 1975 Jan 10;250(1):191-6.
The hydrolysis of MgATP by isolated rat liver mitochondrial ATPase (EC 3.6.1.3) at pH 8.0 was stimulated by various anions. The rate of hydrolysis was increased from 18 to 170 mumol per min per mg, a 9.4-fold stimulation, by HSeO3 at 1 mM MgATP. In the absence of a stimulatory anion, reciprocal plots of initial velocity studies with MgATP as the variable substrate were curved (Hill coefficient approximately 0.5). With the addition of anion, the reciprocal plots became linear. When the substrate was MgITP or MgGTP with the isolated enzyme or MgATP with submitochondrial particles, no curvature of the reciprocal plots was observed. With purified ATPase, anions stimulated the hydrolysis of MgITP, MgGTP, MgUTP or MgCTP only slightly. With submitochondrial particles the stimulation by anions of MgATP hydrolysis was limited to approximately 2-fold. These data are interpreted to indicate the existence of two substrate sites for MgATP and an anion-binding site on the isolated enzyme.
在pH 8.0条件下，分离的大鼠肝脏线粒体ATP酶（EC 3.6.1.3）对MgATP的水解受到各种阴离子的刺激。在1 mM MgATP存在时，HSeO3可将水解速率从每分钟每毫克18微摩尔提高到170微摩尔，刺激倍数为9.4倍。在没有刺激阴离子的情况下，以MgATP作为可变底物进行的初始速度研究的双倒数图呈曲线（希尔系数约为0.5）。加入阴离子后，双倒数图变为线性。当底物为MgITP或MgGTP（与分离的酶）或MgATP（与亚线粒体颗粒）时，未观察到双倒数图的曲率。对于纯化的ATP酶，阴离子仅轻微刺激MgITP、MgGTP、MgUTP或MgCTP的水解。对于亚线粒体颗粒，阴离子对MgATP水解的刺激仅限于约2倍。这些数据被解释为表明在分离的酶上存在两个MgATP底物位点和一个阴离子结合位点。
