title: Novel carbohydrate structures of cathepsin B from porcine spleen.
abstract: Two 13-residue glycopeptides were isolated from the digestion of purified porcine spleen cathepsin B by Staphylococcus aureus protease using high performance liquid chromatography. The major peptide, which is about 73% of the total, had the amino acid sequence His-His-Val-Asn(CH2O)-Gly-Ser-Arg-Pro-Pro-Cys-Thr-Gly-Glu. This peptide contains only a single N-acetylglucosamine residue linked to asparagine at the fourth residue by a beta-linkage. The minor peptide had a single amino acid replacement in a sequence otherwise identical to that of the major peptide. A serine was found at residue 10 instead of a half-cystine. The minor peptide also contains different carbohydrates, which were determined using proton NMR to be Man alpha 1----6 Man beta 1----4 GlcNAc beta 1----4(Fuc alpha 1----6)GlcNAc beta 1----n Asn. These results suggest that the cathepsin B carbohydrates are processed in vivo by enzymic systems specific to each isozyme.
mesh_terms: D000117:Acetylglucosamine / Q000032:analysis; D000595:Amino Acid Sequence; D000818:Animals; D001216:Asparagine / Q000032:analysis; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000032:analysis; D002401:Cathepsin B; D002403:Cathepsins / Q000302:isolation & purification*; D006020:Glycopeptides / Q000302:isolation & purification; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D013154:Spleen / Q000201:enzymology*; D013552:Swine
chemical_list: D002241:Carbohydrates; D006020:Glycopeptides; D046911:Macromolecular Substances; D001216:Asparagine; D002403:Cathepsins; D002401:Cathepsin B; D000117:Acetylglucosamine