ISOLATION AND CHARACTERIZATION OF TWO β(1)-GLYCOPROTEINS OF HUMAN SERUM

Two immunoelectrophoretically defined, heretofore unidentified β(1)-globulins of human serum, provisionally designated β(1C)- and β(1A)-globulin, were isolated by means of preparative electrophoresis and chromatography on anion exchange cellulose. The sedimentation coefficient S(0) (20, w) of β(1C)-globulin was shown to be 9.5 S, and that of β(1A)-globulin, 6.9 S. Both proteins were found to contain similar amounts of carbohydrate, to be devoid of lipids, and to possess the solubility characteristics of euglobulins. In the Ouchterlony double diffusion test they gave the reaction of partial identity, which revealed β(1A)-globulin to be anti-genically deficient as compared to β(1C)-globulin. β(1A)-globulin could not be detected in fresh sera and β(1C)-globulin was absent from aged sera. Highly purified β(1C)-globulin stored at 1°C. was converted to β(1A)-globulin within 4 to 6 weeks, and at 37°C. was converted within 6 days. The likelihood of a dimer-monomer relationship between these two proteins was discussed.