Equilibrium binding studies with ATPase isolated from Rhodospirillum rubum chromotophores have been carried out using gel filtration. Binding experiments with variable concentrations of [14C]ADP show a biphasic saturation curve. With a parameter fitting computer program the dissociation constants for two distinct binding sites are determined as 7 x 10(-6) and 9 x 10(-5) M, respectively. The enzyme-bound radioactivity is recovered as ADP (80-90%), and the rest is converted to AMP and ATP. In the free nucleotides a large amount of AMP (about 70%) is found in addition to ADP. Analogous binding experiments with [14C]ATP are monophasic. Most of the bound radioactivity can be identified as ADP showing a dissociation constant corresponding to the high affinity site. The pattern of the free nucleotides is the same as in the experiments with ADP. These results indicate three separate binding sites on the enzyme: a low and a high affinity site for ADP, and a site at which ATP hydrolysis takes place. The analysis of the nucleotides suggests for the ADP sites a phosphoryl group transfer to produce ATP and AMP. Various experiments exclude the contamination of the enzyme preparation with adenylate kinase.

中文翻译：

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腺嘌呤核苷酸对来自红色红螺菌的纯化偶联因子的结合和反应研究。

已经使用凝胶过滤对从红螺菌发色团中分离的 ATP 酶进行了平衡结合研究。[14C]ADP 不同浓度的结合实验显示出双相饱和曲线。使用参数拟合计算机程序，两个不同结合位点的解离常数分别确定为 7 x 10(-6) 和 9 x 10(-5) M。酶结合的放射性以 ADP (80-90%) 形式回收，其余部分转化为 AMP 和 ATP。在游离核苷酸中，除了 ADP 外，还发现了大量的 AMP（约 70%）。[14C]ATP 的类似结合实验是单相的。大多数结合的放射性可以被鉴定为 ADP，显示出对应于高亲和力位点的解离常数。游离核苷酸的模式与 ADP 实验中的相同。这些结果表明酶上有三个独立的结合位点：ADP 的低亲和力和高亲和力位点，以及发生 ATP 水解的位点。核苷酸的分析表明 ADP 位点发生了磷酰基转移以产生 ATP 和 AMP。各种实验排除了酶制剂被腺苷酸激酶污染。