Extension of kinetic model for superoxide dismutase inactivation to the irradiated manganese tetramer.

Abstract Nitrous oxide-saturated, aqueous solutions of human manganesesuperoxide dismutase were irradiated with 60 Co gamma rays to study inactivation of the enzyme. The dose responses were linearized by plotting the reciprocal of the enzyme activity remaining against dose, thus indicating a second-order reaction in the enzyme. A previously described kinetic model, which assumes that damage is transferred intermolecularly through subunit exchange, can be extended to include the present results.