[The role of magnesium ions in the regulation of the catalytic activity of kidney Na+,K+-ATPase].
Free Mg2+ is studied for its effect on the activation kinetics of pig kidney Na+, K+-ATPase by monovalent cations (nH and K0.5 for Na+ and K+ are determined). It is established that at the saturating concentration of complementary ion-activator an increase of free Mg2+ concentration up to 12 mM is accompanied by a rise of nH and K0.5 for Na+ and a fall of K0.5 for K+ without nH changes for this cation. The analysis of inhibition kinetics shows that free Mg2+ is a competitive inhibitor as to Na+ and noncompetitive as to K+. It is concluded that inhibition of Na+, K+-ATPase by free Mg2+ is a complex process including competition with Na+ at its binding sites and the "occluding" of enzyme at the stage, preceding dissociation of cation and also the weakening of subunit interactions in the enzyme.
Kaplia
A A
AA
Kravtsov
A V
AV
Kravtsova
V V
VV
Slutskaia
N P
NP
Gorishniak
V P
VP
D000818:Animals; D001665:Binding Sites; D002384:Catalysis; D004789:Enzyme Activation; D066298:In Vitro Techniques; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013552:Swine
D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium
Rol' ionov magniia v reguliatsii kataliticheskoĭ aktivnosti Na+,K+-ATP-azy pochek.