Mechanism of oxidative damage of dog kidney Na/K-ATPase.

Oxidative modification of kidney Na/K-ATPase was found to be accompanied by a decrease in the amount of sulfhydryl groups accessible for Elmann reagent with subsequent transformation of kinetic behavior of the enzyme. Oxidation of Na/K-ATPase with 20 mM hydrogen peroxide during 20 min results in about 50% inhibition of its activity and subsequent transformation of complex substrate-velocity dependence into the simple hyperbolic curve. In terms of kinetic analysis the suggestion was made that partial oxidation of Na/K-ATPase by hydrogen peroxide results in disordering of interprotomer interaction in the oligomeric complex of Na/K-ATPase.