Radiation induces the change of specific ferroxidase activity in rat antioxidant protein ceruloplasmin

Male rats were exposed to a whole body with a single dose of 4.0Gy. The animals were sacrificed 68 hours following exposure. The specific amine (ο-dianixidine) oxidase activity of ceruloplasmin purified from the γ-irradiated rat serum was not different from that of normal ceruloplasmin. On the other hand, the specific ferroxidase activity of ceruloplasmin from the γ-irradiated rat serum was 2.5 fold as high as compared to that of normal ceruloplamsin. The copper content in ceruloplasmin was also changed from 5.9 copper/molecule to 4.5 copper/ molecule. It may be that irradiation induces the structural change of ceruloplasmin in the biosynthetic process. The ferroxidase activity of ceruloplasmin prevents free Fe2+, which can be released by γ-irradiation, from producing oxygen free radicals in the presence of H2O2