抄録
IgG type of immunoglobulins was isolated from normal bovine colostrum and further fractionated by anion-exchange chromatography to yield IgG2 and IgG1 fractions. Immunoelectrophoresis showed that the IgG1 fraction contained a heterogeneous population with different charges, but no further structural differences were found on both digestion and reduction experiment within this IgG1 population.
The IgG2 fraction showed strong resistance to digestion with pepsin and papain, while the IgG1 fraction was easily digested. Treatment with cysteine and DTT showed that the IgG2 fraction was easily reduced, producing an appreciable amount of H-L half molecules, H chains, and L chains. Under identical conditions, however, only a negligible amount of H-L and H was produced from the IgG1 fraction. Thus it was suggested that the differential susceptibility to proteolytic enzymes found between IgG2 and IgG1 should not be correlated with the difference in the number of interheavy chain disulfide binding.
