内源性调节剂对钠钾ATP酶的抑制动力学（II - A）。

Kinetics of Na+, K+-ATPase inhibition by an endogenous modulator (II-A).

作者信息

Reinés A, Peña C, Rodríguez de Lores Arnaiz G

机构信息

Instituto de Biología Celular y Neurociencias, Prof. Eduardo De Robertis, PROBICENE-CONICENT, Facultad de Medicina, Universidad de Buenos Aires, Argentina.

出版信息

Neurochem Res. 2000 Jan;25(1):121-7. doi: 10.1023/a:1007599718356.

DOI:10.1023/a:1007599718356

PMID:10685611

Abstract

We have previously reported the isolation by gel filtration and anionic exchange HPLC of two brain Na+, K+-ATPase inhibitors, II-A and II-E, and kinetics of enzyme interaction with the latter. In the present study we evaluated the kinetics of synaptosomal membrane Na+, K+-ATPase with II-A and found that inhibitory activity was independent of ATP (2-8 mM), Na+ (3.1-100 mM), or K+ (2.5-40 mM) concentration. Hanes-Woolf plots showed that II-A decreases Vmax in all cases; KM value decreased for ATP but remained unaltered for Na+ and K+, indicating respectively uncompetitive and noncompetitive interaction. However, II-A became a stimulator at 0.3 mM K+ concentration. It is postulated that brain endogenous factor II-A may behave as a sodium pump modulator at the synaptic region, an action which depends on K+ concentration.

摘要

我们之前报道过通过凝胶过滤和阴离子交换高效液相色谱法分离出两种脑钠钾ATP酶抑制剂II - A和II - E，以及该酶与后者相互作用的动力学。在本研究中，我们评估了突触体膜钠钾ATP酶与II - A的动力学，发现抑制活性与ATP（2 - 8 mM）、Na⁺（3.1 - 100 mM）或K⁺（2.5 - 40 mM）的浓度无关。汉尼斯 - 伍尔夫图表明，在所有情况下II - A均降低Vmax；ATP的KM值降低，但Na⁺和K⁺的KM值保持不变，分别表明存在非竞争性和非竞争性相互作用。然而，在0.3 mM K⁺浓度下，II - A成为一种刺激剂。据推测，脑内源性因子II - A可能在突触区域作为钠泵调节剂发挥作用，这种作用取决于K⁺浓度。