Isolation of the gamma-C-globulin of bovine cerebrospinal fluid.

Abstract

The γc-globulin of bovine cerebrospinal fluid (CSF) was isolated in immunologically pure form from the globulin fraction of CSF or milk whey by gel filtration on Sephadex G-75. The globulin fraction was obtained by precipitation with sodium or ammonium sulfate rather than by DEAE chromatography because salt precipitation resulted in greater yields of the γc-globulin. When the protein was isolated from bovine colostral whey, about 90% of the immunoglobulin G (IgG) globulin was removed by a preliminary filtration of the whey on Sephadex G-75. The fraction containing the γc-globulin admixed with IgG globulin was then re-chromatographed on Sephadex G-75 to remove the IgG globulin. On gel filtration through a column of Sephadex G-75 that had been calibrated with proteins of known molecular weight, the elution volume of the γc-globulin corresponded to a molecular weight of 30 000. Different lots of γc-globulin that contained no detectable impurities by gel-diffusion tests were compared on a weight basis by a quantitative immunochemical method, and were found to have equal immunological activity.