title: Resolution of the charge forms and amino acid sequence and location of a tryptic glycopeptide in rat alpha-lactalbumin.
abstract: Three charge forms of rat alpha-lactalbumin were separated by ion exchange chromatography on DEAE-cellulose. The amino acid composition of each form was similar but they differed in carbohydrate composition. Each form contained a tryptic glycopeptide having a common polypeptide and heteropolysaccharide unit. The tryptic glycopeptide was sequenced and positioned in rat alpha-lactalbumin, which was partially sequenced from residues 1 to 50. The carbohydrate attachment site was at Asn45. Secondary structure calculations predicted that Asn45 is in a beta bend conformation whereas Asn45 in bovine alpha-lactalbumin, a poorly glycosylated protein, is not in a bend conformation.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002241:Carbohydrates / Q000032:analysis; D002417:Cattle; D002848:Chromatography, DEAE-Cellulose; D006020:Glycopeptides / Q000032:analysis*; D006168:Guinea Pigs; D007768:Lactalbumin / Q000302:isolation & purification; D008958:Models, Molecular; D011487:Protein Conformation; D051381:Rats; D013045:Species Specificity; D014357:Trypsin
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D006020:Glycopeptides; D007768:Lactalbumin; D014357:Trypsin