Oligosaccharide and polypeptide homology of lupin (Lupinus luteus L.) acidphosphatase subunits

Peptide mapping of lupin acid phosphatase clearly demonstrated the homology between its two subunits. Sequenced tryptic peptides also showed 78% ident ity (92% similarity) to the red bean acid phosphatase. Peptides exclusive f or the 50-kDa subunit are homologous to N-terminally located sequences in r ed bean acid phosphatase, leading to the assumption that the shorter subuni t of lupin acid phosphatase is generated by the deletion of the N-terminal part of the longer subunit. Carbohydrate moiety was found to be identical i n both subunits. Oligosaccharide chains released by hydrazinolysis from the both subunits were fluorescently labeled and separated by HPLC. The struct ure of oligosaccharides was elucidated by exoglycosidase sequencing. Sevent een percent of isolated glycans were found to be of the high-mannose type, while the rest belonged to plant complex-type structures. Most of the compl ex glycans were fucosylated and xylosylated; some were fucosylated or xylos ylated only. (C) 1998 Academic Press.