Sucrase-isomaltase was purified from rat intestinal microvillus membranes after injection of D-[2-3H]mannose and L-[6-3H]fucose, using a column of monoclonal antibody-protein A-Sepharose. After Pronase digestion and gel filtration of the glycopeptides labelled from both precursors, a major part of the radioactivity was recovered in asparagine-linked complex oligosaccharides, and a smaller amount in partially alkali-labile high-molecular-weight glycopeptides. Only a small amount of [3H]mannose was found in endo-beta-N-acetylglucosaminidase H-sensitive high-mannose oligosaccharides.
