Structural analysis of N-glycans from yellow lupin (Lupinus luteus) seed diphosphonucleotide phosphatase/phosphodiesterase.

N-linked oligosaccharide chains released by hydrazinolysis from yellow lupin seed diphosphonucleotide phosphatase/phosphodiesterase were fluorescence labeled and separated by high performance liquid chromatography (GlycoSep N and GlycoSep H columns). Exoglycosidase sequencing elucidated the structures of 24 separated N-glycans. Thirty percent of isolated glycans were found to be of high-mannose type (three to eight mannosyl residues), 42% were complex type and 26% belonged to paucimannosidic type. Among complex type glycans, structures with Lewis(a) epitope were identified. It is very unusual to find all types of plant N-glycans in one protein. Possible reasons for such a broad spectrum of N-glycan structures are discussed.