Bond G H, Hudgins P M
Biochim Biophys Acta. 1982 May 7;687(2):310-4. doi: 10.1016/0005-2736(82)90560-0.
Na+-ATPase activity is extremely sensitive to inhibition by vanadate at low Na+ concentrations where Na+ occupies only high-affinity activation sites. Na+ occupies low-affinity activation sites to reverse inhibition of Na+-ATPase and (Na+, K+)-ATPase activities by vanadate. This effect of Na+ is competitive with respect to both vanadate and Mg2+. The apparent affinity of the enzyme for vanadate is markedly increased by K+. The principal effect of K+ may be to displace Na+ from the low-affinity sites at which it activates Na+-ATPase activity.
在低钠浓度下，当钠离子仅占据高亲和力激活位点时，钠钾ATP酶活性对钒酸盐的抑制极为敏感。钠离子占据低亲和力激活位点以逆转钒酸盐对钠钾ATP酶和（钠，钾）-ATP酶活性的抑制作用。钠离子的这种作用在钒酸盐和镁离子方面均具有竞争性。钾离子可显著提高该酶对钒酸盐的表观亲和力。钾离子的主要作用可能是将钠离子从激活钠钾ATP酶活性的低亲和力位点上置换下来。
