Free fatty acids and (Na+,K+)-ATPase: effects on cation regulation, enzyme conformation, and interactions with ethanol.
Free fatty acids and (Na+,K+)-ATPase: effects on cation regulation, enzyme conformation, and interactions with ethanol.
复制标题
游离脂肪酸和 (Na ,K )-ATP 酶：对阳离子调节、酶构象以及与乙醇相互作用的影响。
DOI：
10.1016/0003-9861(84)90456-9
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发表时间：
1984
影响因子：
3.9
通讯作者：
Swann,AC
中科院分区：
文献类型：
--
作者：
Swann,AC
摘要研究了游离脂肪酸对与酶构象有关的(Na+，K+)-ATPase调控参数的影响。对游离脂肪酸抑制的敏感性随着双键数目的增加而增加。游离脂肪酸降低了其调节部位对K+或Na+的亲和力，而不改变其高亲和力部位的表观K+亲和力，并增加了对ATP的表观亲和力。脂肪酸降低了表观E_2、E_1比值和表观Δ_H、Δ、E_1-E_2转换的时间。高K+或低温降低了酶对游离脂肪酸抑制的敏感性。在低K+存在时，花生四烯酸增强了乙醇对磷酸酶活性的抑制作用。单独花生四烯酸对哇巴因结合率影响不大，但在K+存在时加快了哇巴因结合率。这些数据表明，脂肪酸通过阻止单价阳离子介导的向E_2的转变来改变(Na~+，K~+)-ATPase。(Na~+，K~+)-ATPase在体内可能受到磷脂酶释放的游离脂肪酸或缺氧时的影响，或受膜脂饱和的影响。
Abstract Effects of free fatty acids on parameters of (Na+, K+)-ATPase regulation related to enzyme conformation were examined. Sensitivity to inhibition by free fatty acid increased as the number of double bonds increased. Free fatty acids reduced affinity for K+ or Na+ at their regulatory sites without altering apparent K+ affinity at its high-affinity site, and increased apparent affinity for ATP. The apparent E2 E1 ratio and apparent ΔH and ΔS for the E1–E2 transition were reduced by fatty acid. High K+ or low temperature reduced the sensitivity of enzyme to inhibition by free fatty acid. In the presence of low K+, arachidonic acid potentiated inhibition of phosphatase activity by ethanol. Arachidonic acid alone had little effect on the rate of ouabain binding, but accelerated ouabain binding in the presence of K+. These data suggest that fatty acids alter (Na+, K+)-ATPase by preventing the univalent cation-mediated transition to E2, the K+-sensitive form of enzyme.(Na+, K+)-ATPase could potentially be influenced in vivo by free fatty acids released by phospholipases or during hypoxia, or by changes in membrane lipid saturation.