Rabbit ceruloplasmin: purification and partial characterization

Rabbit ceruloplasmin (Cp) was purified after solid ammonium sulfate precipitation to 60% final saturation by a two-step column chromatography procedure, utilizing DEAE-Sephadex A-50 and changing the NaCl concentration in the buffer to 0.16 M to achieve the isolation of the protein. The purified Cp was used to prepare antibodies in guinea pigs that were used afterwards to determine the Cp concentration in normal rabbits and in rabbits with an experimentally induced chronic anemia. The molecular weight of rabbit Cp determined by SDS-PAGE was 125,000 and a high molecular weight Cp of 200,000 comprising 8% of the total purified protein was also found. An optical density ratio (610 nm/280 nm) of 0.0475 and a molar extinction coefficient of 7625 were obtained. Copper determinations yielded a value of 0.24% that corresponds to 5 copper atoms per molecule. The staining of Cp following discelectrophoresis in polyacrylamide gels also showed a two band pattern.