Giunta C, De Bortoli M, Stacchini A, Sanchini M
Comp Biochem Physiol B. 1984;79(1):71-4. doi: 10.1016/0305-0491(84)90079-8.
Na+/K+-ATPase was prepared from Xenopus laevis epidermis. Purification was obtained by ultracentrifugation on sucrose discontinuous gradient. The maximum of enzyme-containing membranes was concentrated in the denser sucrose layer, exhibiting a good and long-lasting activity (specific activity about 55 mumoles of ATP hydrolyzed/mg of protein/hour). The Kd for the ouabain of kidney and epidermis enzymes were very low (in purified preparations respectively 16 nM for kidney enzyme and 4 nM for skin enzyme), indicating a very high sensitivity toward the cardioglycoside. The dose-response graphs of kidney and skin Na+/K+-ATPase vs ouabain concentrations show that at ouabain concentrations ranging from 1 nM and 1 pM the inhibition elicited by the cardioglycoside disappears and is replaced by an activatory effect. At cardioglycoside concentrations higher than 1 nM, the graphs show the typical inhibition curve.
钠钾ATP酶是从非洲爪蟾表皮制备的。通过在蔗糖不连续梯度上进行超速离心实现纯化。含酶膜的最大值集中在密度较大的蔗糖层中，表现出良好且持久的活性（比活性约为每毫克蛋白质每小时水解55微摩尔ATP）。肾脏和表皮酶对哇巴因的解离常数非常低（在纯化制剂中，肾脏酶分别为16 nM，皮肤酶为4 nM），表明对强心苷具有非常高的敏感性。肾脏和皮肤钠钾ATP酶与哇巴因浓度的剂量反应图表明，在哇巴因浓度为1 nM至1 pM范围内，强心苷引起的抑制作用消失，并被激活作用所取代。在强心苷浓度高于1 nM时，图表显示典型的抑制曲线。
