FRACTIONATION OF BOVINE GAMMA-GLOBULIN ON COLUMNS OF CARBOXYMETHYL- AND DIETHYLAMINETHYL-CELLULOSE
Abstract:
Chromatographic fractionation of bovine gamma-globulin was carried out in columns of ion-exchangers -- cellulose derivatives. The gamma-globulin preparation was obtained by the rivanol method. It is shown that when bovine serum or plasma is precipitated by rivanol the hemoglobin admixture which is always present remains in solution and contaminates the gamma-globulin. A method of supplementary purification is proposed which permits separation of the hemoglobin by salting off with ammonium sulfate. The resultant gamma-globulin preparation is found to be electrophoretically homogeneous in phosphate and veronal buffers of pH 7.1, 7.7, and 8.6. The protein is chromatographed on a cation-exchange adsorbent -- carboxymethyl cellulose CM-cellulose, and on an anion-exchange adsorbent -- diethylaminethyl cellulose DEAE-cellulose. In all cases the method of elution by degrees was employed. Conditions have been worked out under which bovine gamma-globulin on CM-cellulose can be separated into seven microfractions by sodium chloride solutions of increasing concentration. In chromatography on DEAE-cellulose it is demonstrated that a change in pH of the eluting solutions from 8.0 to 4.5 makes it impossible to fractionate the protein. Conditions have been worked out under which bovine gamma-globulin may be separated into 11 or 12 microfractions also by changing the sodium chloride concentration in the eluent.