AbstractThis report together with the paper by T. Mizuochi, M. W. Spellman, M. Larkin, J. Solomon, L. J. Basa and T. Feizi (1988) Biochem. J. 254, 599–603 describes the structural elucidation of the N‐linked oligosaccharides of the HIV envelope glycoprotein, gp120 (cloned from the HTLV‐III B isolate and expressed as a secreted fusion protein after transfection of Chinese hamster ovary cells), which is known to bind with high affinity to human T4 lymphocytes. Oligosaccharides were released from peptide by hydrazinolysis, fractionated by paper electrophoresis, high performance lectin affinity chromatography and Bio‐Gel P‐4 column chromatography, and their structures determined by sequential exoglycosidase digestions in conjunction with methylation analysis. The glycoprotein was found to be unique in its diversity of oligosaccharide structures. These include high‐mannose type and hybrid type, as well as four categories of complex type chains: mono‐, bi‐, tri‐ and tetra‐antennary, with or without N‐acetyllactosamine repeats, and with or without a core region fucose residue. Among the sialidase‐treated oligosaccharides no less than 29 structures were identified as follows:
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where G=galactose; GN=N‐acetylglucosamine; M=mannose; F=fucose; ±=residues present in a proportion of chains. The actual number of oligosaccharide structures is much greater since before desialylation there was evidence that among the hybrid and complex type chains all but 6% contained sialic acid at the C‐3 position of terminal galactose residues, and partially sialylated forms of the bi‐ and multiantennary chains were present.
