Characterization of the oligosaccharide structures on bee venom phospholipase A2.

The N-linked oligosaccharide structures on bee venom phospholipase A2 were investigated. The oligosaccharides on purified phospholipase A2 were released by hydrazinolysis and labeled in vitro by reduction with NaB3H4. Following purification, the labeled oligosaccharides were characterized by size exclusion chromatography in combination with digestion with specific glycosidases. Linkage positions were determined by methylation analysis. Four types of structures were identified on the molecule, all of which were of truncated high-mannose type and none of which contained any alpha-(1-->2)-linked mannose residues. The majority of the structures were Man3 oligosaccharides with (43%) or without (38%) a fucose residue linked alpha-(1-->6) to the reducing N-acetylglucosamine. The remaining 19% of the oligosaccharides on the molecule were identified as a Man5 oligosaccharide without core fucose (9.6%) and a core-fucosylated Man4 structure (9.2%).