Effect of hydrogen peroxide on the @entity68 -containing @entity224 dismutase of XXXX .

@entity2769 @entity1522 @entity274 @entity921 @entity68 @entity3793 @entity2340 @entity2975 @entity17643 @entity224 @entity526
The @entity68 -containing @entity224 dismutase from @entity526 is inactivated by @entity274 to a limit of approximately 90%. When corrected for the @entity274 -resistant portion, this inactivation was first order with respect to residual activity and exhibited a pseudo-first-order rate constant of 0.066 min-1 at 25 degrees C in 0.24 mM @entity274 at pH 7.8. The @entity224 dismutase activity remaining after treatment with @entity274 differed from the activity of the native enzyme with respect to heat stability, inhibition by @entity2769 , and inactivation by light in the presence of rose bengal and by @entity17643 . The native and the @entity274 -modified enzymes were indistinguishable by electrophoresis on @entity2975 gels. Inactivation of the enzyme by @entity274 was accompanied by loss of @entity2340 and some loss of @entity68 , but there was no detectable loss of @entity3793 or of other @entity1522 . @entity274 treatment caused changes in the optical spectrum of the enzyme. Inactivation of the enzyme by @entity274 depends upon the @entity68 at the active site. Thus, the apoenzyme and the @entity921 -substituted enzyme were unaffected by @entity274 . We conclude that reaction of @entity274 with the @entity68 at the active site generates a potent oxidant capable of attacking @entity2340 residues. A mechanism is proposed.
