Deguchi T
J Biol Chem. 1977 Nov 10;252(21):7617-9.
When the crude mitochondrial fraction of rat brain was homogenized with distilled water and centrifuged, most of guanylate cyclase activity was detected in the soluble fraction. The total guanylate cyclase activity recovered in the soluble fraction was 5- to 8-fold higher than that of the crude mitochondrial fraction. The greater recovery of guanylate cyclase activity was found to be due to a release of an endogenous activating factor for guanylate cyclase. The activating factor was partially purified by acid extraction followed by a gel filtration and ion exchange resin columns. The factor was a dialyzable small molecule. The molecular weight was estimated to be between 300 and 600 by a Sephadex G-15 column and Diaflo ultrafilter membranes. It was stable in dilute acids, but labile in alkaline solution. It was readily soluble in water, but insoluble in organic solvents. Treatment with various enzymes, so far as tested, failed to abolish the activity. The activating factor stimulated the initial velocity of the reaction. It altered neither the Km value for GTP nor the dependency of the enzyme on divalent metals. The activation by the factor was due to an increase in the Vmax of the reaction. The activation was prevented by lysolecithin, Lubrol PX, hydroxylamine, methylhydroxylamine, or hemoglobin.
将大鼠脑的粗线粒体部分用蒸馏水匀浆并离心后，大部分鸟苷酸环化酶活性在可溶性部分被检测到。可溶性部分中回收的鸟苷酸环化酶总活性比粗线粒体部分高5至8倍。发现鸟苷酸环化酶活性的更高回收率是由于鸟苷酸环化酶内源性激活因子的释放。通过酸提取，然后经凝胶过滤和离子交换树脂柱对激活因子进行部分纯化。该因子是一种可透析的小分子。通过Sephadex G - 15柱和Diaflo超滤膜估计其分子量在300至600之间。它在稀酸中稳定，但在碱性溶液中不稳定。它易溶于水，但不溶于有机溶剂。就目前所测试的各种酶处理而言，均未能消除其活性。该激活因子刺激反应的初始速度。它既不改变GTP的Km值，也不改变酶对二价金属的依赖性。该因子的激活是由于反应的Vmax增加。溶血卵磷脂、Lubrol PX、羟胺、甲基羟胺或血红蛋白可阻止这种激活。
