钒酸盐对人肾钾依赖性磷酸酶的作用。

The effect of vanadate on human kidney potassium dependent phosphatase.

作者信息

Nieder G L, Corder C N, Culp P A

出版信息

Naunyn Schmiedebergs Arch Pharmacol. 1979 Jun;307(2):191-7. doi: 10.1007/BF00498463.

Abstract

This study examined the effects of vanadate on the potassium dependent phosphatase activity present in purified human kidney microsomal (Na+ + K+)-adenosine triphosphatase. Vanadate anion inhibited the K+-dependent phosphatase at a K1 of 35 nM. This inhibition was noncompetitive with the substrate, p-nitrophenylphosphate. The inhibition by vanadate at 1 mM K+ was only 45% of the inhibition that was observed at 10 mM K+. Neither preincubation of the enzyme with vanadate, nor changing the pH of the assay from 8.2 to 7.2 had any effect on the K1 for vanadate. The inclusion of 2.5 mM isoproterenol, to complex the yanadate, reversed the inhibition, as did diluting the enzymatic reaction. Vanadate also inhibited the overall (Na+ + K+)-ATPase reaction at a K1 of 1.91 microM. This inhibition was also reversible upon inclusion of isoproterenol in the assay. Increasing the level of magnesium from 6 mM to 30 mM lowered the K1 of vanadate to 0.25 microM. The possible role of vanadate as a physiological mediator of (Na+ + k+)-atpase activity is discussed.

摘要

本研究检测了钒酸盐对纯化的人肾微粒体（Na⁺ + K⁺）-腺苷三磷酸酶中钾依赖性磷酸酶活性的影响。钒酸根阴离子以35 nM的K₁抑制钾依赖性磷酸酶。这种抑制作用对底物对硝基苯磷酸是非竞争性的。在1 mM K⁺时钒酸盐的抑制作用仅为在10 mM K⁺时观察到的抑制作用的45%。酶与钒酸盐预温育，或将测定的pH从8.2变为7.2，对钒酸盐的K₁均无任何影响。加入2.5 mM异丙肾上腺素以络合钒酸盐，可逆转抑制作用，稀释酶促反应也可逆转抑制作用。钒酸盐还以1.91 μM的K₁抑制总体（Na⁺ + K⁺）-ATP酶反应。在测定中加入异丙肾上腺素后，这种抑制作用也是可逆的。将镁离子浓度从6 mM提高到30 mM可将钒酸盐的K₁降至0.25 μM。本文讨论了钒酸盐作为（Na⁺ + K⁺）-ATP酶活性生理介质的可能作用。