Hansen O
Institute of Physiology, Aarhus University, Denmark.
Biochim Biophys Acta. 1989 Nov 17;986(1):130-4. doi: 10.1016/0005-2736(89)90281-2.
The candidateship of unsaturated fatty acids as endogenous ouabain-like factors was studied. Binding of the artificial ligand vanadate at the intracellular phosphorylation epitope of membrane-bound Na+/K+-ATPase was unaffected by linoleic and arachidonic acid. In the (Mg2+ + Pi)-facilitated system for ouabain binding they were characterized as noncompetitive inhibitors of cardiac glycoside binding, however. The ouabain binding capacity as well as the affinity decreased and the ouabain dissociation rate was accelerated by fatty acids. In the presence of vanadate for facilitation of ouabain binding an increase in ouabain affinity was seen. It is concluded that elementary criteria for the characterization of unsaturated fatty acids as ouabain-like factors are not fulfilled. The ratio between E2-subconformations of Na+/K+-ATPase with different ouabain affinities may be changed by incorporation of fatty acids in the lipid membrane.
对不饱和脂肪酸作为内源性哇巴因样因子的候选情况进行了研究。人工配体钒酸盐在膜结合型钠钾ATP酶的细胞内磷酸化表位处的结合不受亚油酸和花生四烯酸的影响。然而，在（镁离子+无机磷酸）促进哇巴因结合的系统中，它们被表征为强心苷结合的非竞争性抑制剂。脂肪酸会降低哇巴因结合能力和亲和力，并加速哇巴因解离速率。在存在钒酸盐以促进哇巴因结合的情况下，可观察到哇巴因亲和力增加。得出的结论是，不饱和脂肪酸作为哇巴因样因子的基本表征标准未得到满足。不同哇巴因亲和力的钠钾ATP酶E2亚构象之间的比例可能会因脂肪酸掺入脂质膜而改变。
