Soong K S, Wang J H
Biochemistry. 1984 Jan 3;23(1):136-41. doi: 10.1021/bi00296a022.
Bovine heart mitochondrial adenosinetriphosphatase selectively labeled by [14C]-N,N'-dicyclohexylcarbodiimide or [14C]-7-chloro-4-nitro-2,1,3-benzoxadiazole was used together with other components to form reconstituted submitochondrial particles. When assayed for ATP hydrolysis under normal hydrolysis condition, these labeled submitochondrial particles were found to increase slowly in specific activity with preincubation time, without losing the covalent label. But when assayed for oxidative phosphorylation, the ratio of the specific activity of the same labeled particles to that of the control particles was higher and was unaffected by preincubation. If the labeled particles had been treated by a simulated procedure for oxidative phosphorylation measurement before the ATPase assay, their specific activities for ATP hydrolysis were also found to be higher and unaffected by preincubation. These observations are difficult to reconcile with the alternating three-site model for proton adenosinetriphosphatase or any model which requires the sequential action of three identical sites for ATP hydrolysis and synthesis. A new model with one active and two latent interacting sites is proposed for interpreting the present data.
用[¹⁴C]-N,N'-二环己基碳二亚胺或[¹⁴C]-7-氯-4-硝基-2,1,3-苯并恶二唑选择性标记的牛心线粒体腺苷三磷酸酶与其他成分一起用于形成重组亚线粒体颗粒。在正常水解条件下测定ATP水解时，发现这些标记的亚线粒体颗粒的比活性随预孵育时间缓慢增加，且未丢失共价标记。但在测定氧化磷酸化时，相同标记颗粒的比活性与对照颗粒的比活性之比更高，且不受预孵育的影响。如果在进行ATP酶测定之前，已对标记颗粒进行了模拟氧化磷酸化测量的处理，则还发现它们的ATP水解比活性更高，且不受预孵育的影响。这些观察结果难以与质子腺苷三磷酸酶的交替三位点模型或任何需要三个相同位点依次作用进行ATP水解和合成的模型相协调。提出了一个具有一个活性位点和两个潜在相互作用位点的新模型来解释目前的数据。
