Weber J, Senior A E
University of Rochester Medical Center, Department of Biochemistry, NY 14642, USA.
Biochim Biophys Acta. 1996 Jul 18;1275(1-2):101-4. doi: 10.1016/0005-2728(96)00057-6.
Using strategically-placed tryptophan (Trp) residues as optical probes to monitor nucleotide binding and hydrolysis, we demonstrate that all three catalytic nucleotide binding sites in F1-ATPase must be filled to obtain physiological (Vmax) MgATP hydrolysis rates. At Vmax hydrolysis rates, the predominant enzyme species has one of the three catalytic sites filled with unhydrolyzed substrate MgATP, the other two sites are filled with product MgADP. A specifically-inserted Trp probe was also developed to characterize nucleotide binding to the noncatalytic sites, and a model to explain the specificity of these sites is shown. These sites appear to play no role in ATP hydrolysis.
利用精心定位的色氨酸（Trp）残基作为光学探针来监测核苷酸结合和水解，我们证明F1-ATP酶中所有三个催化性核苷酸结合位点都必须被占据，才能获得生理状态下的（最大反应速度Vmax）MgATP水解速率。在Vmax水解速率下，主要的酶形式是三个催化位点中的一个被未水解的底物MgATP占据，另外两个位点被产物MgADP占据。还开发了一种特异性插入的Trp探针来表征核苷酸与非催化位点的结合，并展示了一个解释这些位点特异性的模型。这些位点似乎在ATP水解中不起作用。
