Human monoclonal cryoimmunoglobulins. II. Comparative studies on the carbohydrate contents and compositions of cryoglobulins and myeloma proteins.
The carbohydrate contents and compositions of cryoglobulins and myeloma proteins were comparatively investigated by gas-liquid chromatographic and colorimetric analyses. Human monoclonal cryoglobulins, Jir (IgG3 kappa), Wat (IgG3 lambda), Fji (IgM kappa), and human myeloma proteins, Har (IgGl kappa) and Kob (IgA kappa) were used for the present experiments. The results obtained were that the carbohydrate contents of Jir and Wat were 2.7 and 4.4% in weight basis; the N-acetyl glucosamine of Wat was almost two times higher than that of Jir and no sialic acid was found in both of these proteins; the total carbohydrate content of Fji was 7.7% and the sialic acid content was 19.3% of the total carbohydrate moiety; the myeloma proteins, Har and Kob, contained 5.3 and 10.4% carbohydrate, respectively, and sialic acid was detectable in these proteins. These results indicate that the carbohydrate contents are variable in each of the proteins, but the relative compositions of monosaccharides in individual samples are nearly the same, except for Kob containing O-glycosidic carbohydrate linkages. In addition, the results showing that sialic acid was detectable in Fji, but not in Jir nor Wat, suggested that the lack of terminal carbohydrate residue was not a common structural feature of cryoglobulins, and was not responsible for the temperature-dependent precipitability of these unusual proteins.
Department of Immunology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
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Sakai
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Nakamura
D000596:Amino Acids / Q000032:analysis; D002241:Carbohydrates / Q000032:analysis*; D003450:Cryoglobulins / Q000032:analysis*; D006595:Hexosamines / Q000032:analysis; D006801:Humans; D009194:Myeloma Proteins / Q000032:analysis*
D000596:Amino Acids; D002241:Carbohydrates; D003450:Cryoglobulins; D006595:Hexosamines; D009194:Myeloma Proteins