Studies on the fragmentation of human immunoglobulin M by cyanogen bromide

Human IgM proteins have been isolated from several pathological sera by euglobulin precipitation followed by gel filtration. The purity of the isolated IgM proteins was determined by cellulose acetate electrophoresis. By reacting with anti-human IgM serum and anti-human Kappa (K) chain serum the immunological properties were determined. The polymeric IgM molecule (Mol-wt ≈ 950 000) was converted into pentameric Fcμ fragments using trypsin, and into monomer subunites (IgMs) using cysteine, and the purities and immunological characteristics of these products were studied. Their molecular weights were also estimated by gel filtration chromatography and by SDS polyacrylamide gel electrophoresis. [Continues.]