Separation of Hinge Glycopeptides of Human IgD by HPLC
Amino acid sequence analysis of myeloma proteins has established that all five classes of human immunoglobulins have the same tetrachain structural pattern. However, the five classes differ greatly in the structure of the hinge region connecting Fab and Fc (1). Previous studies (2) of the human IgD protein WAH showed that the hinge region has an unusual structure with two dissimilar sections; the C- terminal half, which is highly charged, is extremely sensitive to proteolysis, whereas the N-terminal half is rich in galactosamine (GalN), which may confer on IgD an important function as a cell receptor (3). Determination of the amino acid sequence of the IgD hinge region has been very difficult for several reasons: 1) the heterogeneity and steric hindrance of the carbohydrate chains, 2) difficulty in purification of a series of similar large glycopeptides, 3) technical problems of sequence analysis. To facilitate structural studies of IgD, we have developed reverse phase high pressure liquid chromatography (HPLC) for preparative isolation of glycopeptides.
KeywordsOligosaccharide Threonine Glycopeptide Cacodylate Chymotrypsin
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