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Biomedical subjects

J R Clamp

Publications and source records attributed to J R Clamp.

At least 73 records · Page 4Linked to original sources
PubMed1975

Studies on human IgD myeloma proteins. Carbohydrate composition of intact proteins and some proteolytic fragments.

Human IgD myeloma proteins are shown to have a high carbohydrate content (9-18%) and to exhibit the same heterogeneity in carbohydrate content and composition as myeloma protein of the other immunoglobulin classes. All IgD proteins studied contain N-acetylgalactosamine which is contained in a carbohydrate moiety attached within the "hinge" region of the heavy chain whilst the bulk of the carbohydrate is attached within the Fcdelta region of the molecule.

Acetylgalactosamine↗
PubMed1971

The oligosaccharide units of a human type L immunoglobulin M (Macroglobulin).

1. The carbohydrate composition of the monomeric unit of a type L macroglobulin (immunoglobulin M) was determined as 6 residues of fucose, 35 of mannose, 11 of galactose, 27 of N-acetylglucosamine and 9 of sialic acid. 2. Two types of oligosaccharide unit were present in the protein, one of which (Ca type) contained fucose, mannose, galactose, N-acetylglucosamine and sialic acid in the molar proportions 1:3-4:2:3-5:0-2, and the other (Cb type) contained mannose and N-acetylglucosamine in the proportions 6-8:2-3. 3. A tentative structure is proposed for the Cb type unit. 4. An S-carboxymethylcysteine-containing glycopeptide with a Ca-type unit was isolated after reduction, alkylation and tryptic digestion of the protein. 5. The immunoglobulin monomer appears to contain six oligosaccharide units of the Ca type and two of the Cb type.

Amino Acids↗
PubMed1971

An assessment of methanolysis and other factors used in the analysis of carbohydrate-containing materials.

The stability of monosaccharides in methanolic hydrochloric acid of different strengths and at different temperatures was determined. They are generally stable for 24h in methanolic 1m- and 2m-hydrochloric acid at both 85 degrees C and 100 degrees C, but undergo considerable destruction in methanolic 4m- and 6m-hydrochloric acid at 100 degrees C. Analysis of glycopeptides and oligosaccharides of known composition showed that release of carbohydrate was complete within 3h in methanolic 1m-hydrochloric acid at 85 degrees C. Removal of methanolic hydrochloric acid by rotary evaporation resulted in considerable losses of monosaccharides, which could be prevented by prior neutralization. Methanolysis caused extensive de-N-acetylation of acetamidohexoses, so that a re-N-acetylation step is necessary in the analytical procedure. The addition of acetic anhydride for this purpose also prevented loss of internal standard by adsorption on the insoluble silver salts used in neutralization. Several trimethylsilylating agents were studied and suitable conditions are recommended. The effects on the analytical system of water and some common organic and inorganic contaminants are assessed.

Acetates↗