PRIMARY STRUCTURES OF THE N-LINKED CARBOHYDRATE CHAINS FROM HONEYBEE VENOM PHOSPHOLIPASE-A2

The N-linked carbohydrate chains of phospholipase A2 from honeybee (Ap is mellifera) were released from glycopeptides with peptide-N-glycanas e A and reductively aminated with 2-aminopyridine. The fluorescent der ivatives were separated by size-fractionation and reverse-phase HPLC, yielding 14 fractions. Structural analysis was accomplished by composi tional and methylation analyses, by comparison of the HPLC elution pat terns with reference oligosaccharides, by stepwise exoglycosidase dige stions which were monitored by HPLC, and, where necessary, by 500-MHz H-1-NMR spectroscopy. Ten oligosaccharides consisted of mannose, N-ace tylglucosamine and fucose alpha1-6 and/or alpha1-3 linked to the inner most N-acetylglucosamine. Four compounds, which comprised 10% of the o ligosaccharide pool from phospholipase A2, contained a rarely found te rminal element with N-acetylgalactosamine. The structures of the 14 N- glycans from honeybee phospholipase A2 can be arranged into the follow ing three series: [GRAPHICS]