Isolation and Characterization of the Glycopeptides of Porcine Pancreatic Lipases L and L

The glycopeptides of porcine pancreatic lipases La and Lb have been isolated. Compositional and end group analyses, in addition to enzymatic hydrolysis with carboxypeptidases A and B, suggest the following amino acid sequence: Thr-Asx-Gly-Thr-Ile-Glu-Arg. Pronase digestion yielded a smaller glycopeptide which contained only aspartic acid, threonine, and glycine. The carbohydrate linkage is alkali-stable, indicating that N-acetylglucosamine is involved in an N-acylglucosylamine bond to asparagine. Lipases La and Lb contain fucose and galactose as well as mannose and glucosamine. Lipase La also contains sialic acid and gives rise to a more heterogeneous glycopeptide population upon proteolysis; the heterogeneity is due solely to the carbohydrate moieties.