The composition and structure of the carbohydrate of pineapple stem bromelain.

Two major components of pineapple bromelain, purified to electrophoretical homogeneity, appeared to have the same oligosaccharide group consisting of n-glucosamine, n-mannose, D-xylose, and L-fucose in ratios of 2:2: 1: 1. By exhaustive proteolysis of the bromelains, glycopeptides containing only Asx, Glx, and Ser were obtained. Periodate oxidation, methylation, and glycosidase digestion showed that the oligosaccharide chain has a highly branched structure in which all the neutral sugars are in nonreducing terminal positions and both N-acetyl-D-glucosamine residues occur in internal positions.