[The role of bivalent cations in the binding of hexokinase II isoenzyme to mitochondrial membranes].
A comparative study of Mg2+ and Ca2+ effects on the ability of rat skeletal muscle hexokinase isozyme II to bind mitochondrial membranes isolated from the same source was carried out. It was found that the binding ability of the enzyme increases in a similar way in the presence of equimolar amounts of both cations. The dependence of binding ability on cation concentration is hyperbolic, which points to the existence of specific and equivalent metal binding sites during hexokinase attachment to the membranes. Substitution of Ca2+ for Mg2+ does not influence the tightness of the enzyme binding to membranes, which can be evidenced from the type of dependence of the bound hexokinase solubilization degree on KCl concentration in the eluting buffer. The enzyme absorption mediated by various cations is accompanied by corresponding changes in its kinetic properties (V, Km for glucose, Ki for ADP). The role of bivalent cations in the formation of the specific hexokinase-membrane binding is discussed.
N Iu
NIu
Goncharova
E M
EM
Muntian
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent / Q000494:pharmacology*; D006593:Hexokinase / Q000378:metabolism*; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008931:Mitochondria, Muscle / Q000378:metabolism*; D009132:Muscles / Q000201:enzymology / Q000378:metabolism; D051381:Rats
D002413:Cations, Divalent; D007527:Isoenzymes; D006593:Hexokinase; D008274:Magnesium; D002118:Calcium
Rol' bivalentnykh kationov v sviazyvanii izofermenta II geksokinazy s mitokhondrial'nymi membranami.