哇巴因与磷脂依赖性三磷酸腺苷酶的结合。
Ouabain binding to phospholipid-dependent adenosine triphosphatase.
作者信息
Goodman S L, Wheeler K P
出版信息
Biochem J. 1978 Feb 1;169(2):313-20. doi: 10.1042/bj1690313.
The role of phospholipid in the binding of ouabain to the (Na+ + K+)-dependent adenosine triphosphatase was studied. Enzyme preparations obtained from rabbit kidney were treated with Lubrol WX to remove the phospholipid component essential for ATPase activity. Reconstituted enzyme samples were prepared by the addition of phosphatidylserine and sedimentation of an enzymically active lipid-protein complex. The binding of ouabain to both kinds of preparations was measured under equilibrium conditions with the use of 3H-labelled ouabain and initial ouabain concentrations in the range 0.01-1 micrometer. The main findings were: (i) (Mg2+ + Pi) promoted binding of significant quantities of ouabain only to the reconstituted enzyme; (ii) the absence of added Na+, (Mg2+ + ATP) similarly promoted binding only to the reconstituted samples; (iii) the addition of Na+ in the presence of (Mg2+ + ATP) increased the amount of ouabain bound to the reconstituted enzyme when the ouabain concentration was below about 0.1 micrometer, but it had no effect when the ouabain concentration was about 1 micrometer; (iv) (Mg2+ + ATP) induced ouabain binding to the depleted enzyme only when Na+ was also added; (v) the amount of ouabain bound to both depleted and reconstituted enzymes was the same in the presence of (Mg2+ + ATP + Na+); (vi) the reconstituted enzyme appeared to have a greater affinity for Na+ than did the depleted enzyme.
研究了磷脂在哇巴因与（Na⁺+K⁺）依赖性腺苷三磷酸酶结合中的作用。用Lubrol WX处理从兔肾获得的酶制剂，以去除ATP酶活性所必需的磷脂成分。通过添加磷脂酰丝氨酸和沉淀有酶活性的脂蛋白复合物来制备重组酶样品。在平衡条件下，使用³H标记的哇巴因和初始哇巴因浓度在0.01 - 1微米范围内，测量哇巴因与两种制剂的结合。主要发现如下：（i）（Mg²⁺+Pi）仅促进大量哇巴因与重组酶的结合；（ii）不添加Na⁺时，（Mg²⁺+ATP）同样仅促进与重组样品的结合；（iii）当哇巴因浓度低于约0.1微米时，在（Mg²⁺+ATP）存在下添加Na⁺会增加哇巴因与重组酶的结合量，但当哇巴因浓度约为1微米时则无影响；（iv）仅当添加Na⁺时，（Mg²⁺+ATP）才诱导哇巴因与去磷脂酶结合；（v）在（Mg²⁺+ATP+Na⁺）存在下，与去磷脂酶和重组酶结合的哇巴因量相同；（vi）重组酶对Na⁺的亲和力似乎比去磷脂酶更大。
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