Santiago E, Iriarte A J, López-Zabalza M J, López-Moratalla N
Rev Esp Fisiol. 1980 Mar;36(1):41-7.
The extent of stimulation of the hydrolytic activity of mitochondrial ATPase by the reducing agent dithionite has been found to depend on substrate concentration both for the membrane bound enzyme and for the isolated and purified F1ATPase. The results suggest the existence of three catalytic sites differing in their standard reduction potential. The activating effect of free ATP on the hydrolytic activity of rat liver F1-ATPase has been found to be more pronounced on the reduced form of the enzyme. On the contrary, the inhibitory effect of ADP was higher on the oxidized form of F1-ATPase. Citrate has also been found to be an inhibitor of F1-ATPase; its effect was more pronounced on the reduced form of the enzyme, and exhibited a competitive pattern of inhibition with respect to free ATP. The results obtained have been interpreted in the sense that free ATP and ADP may be modifying the standard reduction potential of the enzyme, and suggest the existence of three independent redox cycles in ATPase governed by the exchange of ADP and Pi for the newly synthesized ATP.
已发现，无论是膜结合酶还是分离纯化的F1ATP酶，还原剂连二亚硫酸盐对线粒体ATP酶水解活性的刺激程度均取决于底物浓度。结果表明存在三个标准还原电位不同的催化位点。已发现游离ATP对大鼠肝脏F1ATP酶水解活性的激活作用在酶的还原形式上更为明显。相反，ADP对F1ATP酶氧化形式的抑制作用更强。还发现柠檬酸盐是F1ATP酶的抑制剂；其作用在酶的还原形式上更为明显，并且相对于游离ATP表现出竞争性抑制模式。所得结果的解释是，游离ATP和ADP可能在改变酶的标准还原电位，并表明在ATP酶中存在由ADP和Pi与新合成的ATP交换所控制的三个独立的氧化还原循环。
