Abstract
1. Human beta(1A)-globulin was isolated from serum by precipitation with ammonium sulphate, gel filtration and electrophoresis in polyacrylamide gel. 2. The product was found by ultracentrifugation, analytical electrophoresis in polyacrylamide gel and two-dimensional immunoelectrophoresis to be of satisfactory quality for further study. 3. The amino acid composition of beta(1A)-globulin was determined. 4. In ordinary dilute buffers near neutrality, beta(1A)-globulin had S(0) (20,w) 6.42s and M 131 000, but some reversible aggregation occurred at lower pH. In neutral 6m-guanidine hydrochloride the molecular weight was not measurably different from that in dilute buffer.