title: Microheterogeneity of Immunoglobulin G from plasmocytomas. Identification of two types of IgG by isoelectric focusing.
abstract: Isoelectric focusing of serum immunoglobulin G (IgG) revealed that the microheterogeneity, which is expressed in the isoelectric points (IEP), partly is caused by differences in the content of N-acetyl-neuraminic acid (NANA), partly by other effects, probably including deamidation. Two different types of Plasmocytoma-IgG, which differ in IEF-pattern, i.e. population distribution, in sensitivity towards neuraminidase and in carbohydrate content, are described. The contents of carbohydrates in these 2 IgG-types are up to 30% greater and 50% less, respectively, than that of normal IgG. A precise correlation was found between the total content of NANA in moles per mole IgG-monomer and the shift in band-IEP on hydrolysis catalyzed by neuraminidase. This may be used for a rapid estimate of NANA in IgG. The results do not permit a discrimination between an anabolic and a catabolic origin of the heterogeneity in the carbohydrate moiety of IgG.
mesh_terms: D000910:Antibodies, Heterophile / Q000032:analysis*; D002241:Carbohydrates / Q000032:analysis; D006801:Humans; D006868:Hydrolysis; D007074:Immunoglobulin G / Q000032:analysis*; D007525:Isoelectric Focusing; D009438:Neuraminic Acids / Q000032:analysis; D009439:Neuraminidase / Q000378:metabolism; D010954:Plasmacytoma / Q000097:blood*
chemical_list: D000910:Antibodies, Heterophile; D002241:Carbohydrates; D007074:Immunoglobulin G; D009438:Neuraminic Acids; D009439:Neuraminidase