Two Types of  -Globulin Differing in Carbohydrate Content

Summary1. The heavy components (19 S) have been highly concentrated from normal human serum by repeated cycling in the preparative ultracentrifuge. Electrophoresis of such preparations has permitted isolation of a high molecular weight γ-globulin fraction. 2. Analyses of this material indicate a high carbohydrate content with hexose sugars and sialic acid present at approximately 5 times the concentration found for the main 7 S γ-globulin. The hexosamine-hexose ratio is approximately 0.5. 3. Markedly reduced levels were found in the sera of 4 patients with agammaglobulinemia. The possibility that certain antibodies fall into the 19 S fraction and are similarly rich in carbohydrate is discussed.