Radiation inactivation of rabbit muscle aldolase

Abstract

Pulse radiolysis and steady-state X-radiolysis have been used to investigate the radiation inactivation of aldolase from rabbit muscle. Both eaq-and OH readily react with aldolase, and contribute to inactivation. The radical anions (CNS)2-and (Br)2-react with aldolase at neutral pH. The progressive addition of alkali results in an increase in the second-order rate constants, with an apparent pK approximately 10 +/- 0-3, and with the formation of an unstable intermediate, lambdamax approximately 400 nm resembling a phenoxyl radical. Steady-state radiolysis in the presence of (CNS)2-and (Br)2- at alkaline pH results in increased aldolase inactivation, with a pK of enzyme inactivation similar to that observed for reaction of the radical anions. We propose that a reaction of the radical anoins with tyrosine residues accounts for the resultant inactivation.