园二色性光谱研究不同醇对猪心线粒体F_1-ATP酶和H~+-ATP酶复合体构象及其与水解活力的关系

本文测定了ATP酶复合体和F_1—ATP酶(简称F_1)在低浓度甲、乙、正丙、异丙、叔丁醇中的远紫外圆二色(CD)光谱。并且比较了二者受这些醇作用时的水解活力变化。 结果表明:除10％—20％正丙醇。20％的乙醇。异丙醇和叔丁醇使F_1的CD双负峰明显变小。α螺旋量减少外其它5％—20％的各种醇均可使F_1的CD谱双负峰略微变大。α—螺旋量也相应变大。而外加5％—20％的各种醇对ATP酶复合体的CD谱影响不大。α—螺旋量也无明显变化。同时发现ATP酶复合体的水解活力不易受这些醇影响,而F_1的水解活力容易受醇类影响。显然,与游离的F_1相比,ATP酶复合体中疏水蛋白(F_0)及部分磷脂的存在,使其构象及水解功能均呈现了对醇的稳定性。水介活性与CD变化之间的关系文中作了讨论。

CIRCULAR DICHROISM STUDIES ON THE EFFECTS OF ALCOHOLS ON CONFORMATION AND HYDROLYTIC ACTIVITY OF MITOCHONDRIAL H~+- ATPase COMPLEX AND F_1- ATPase FROM PIG HEART

The effects of low concentration of methanol, ethanol, n- propanol. i-propanol and t-butanol on the conformation of both F1-ATPase and H+ -ATPase complex were systematically investigated by circular dichroism (CD). The effects of the organic solvents on the hydrolytic activity of both F1 and the complex were also studied.The results indicate that low concentration of alcohols had slight effects on the conformation and hydrolytic activity of H+ -ATPase complex, whereas these alcohols significantly affected the conformation and activity of F1. Our work seems to indicate that the membrane sector F0 and lipids of H+ -ATPase complex may stabilize the conformation of membrane bound F1 containing the catalytic site for ATP hydrolysis. The conformation of F1 in the H+ -ATPase complex state may be different from that in isolated state. The relationship between CD change and hydrolytic activity was discussed.