Comparison of bovine serum transferrin A and D₂. II. Glycopeptides

Abstract

SummaryGlycopeptides are isolated from subtilisin and pronase digests of whole bovine serum transferrin A and D2. The two variants yield glycopeptides with identical ami‐no acid composition. Hence, there is probably no amino acid substitution in this region of the peptide chain. Amino acid sequence determination of one glycopeptide (subtilisin glycopeptide 8) gives the sequence: (CHO)Asn‐Ser‐Ser‐Leu‐Cys. This sequence is identical with that of residues 491–495 of the sequence for human serum transferrin (MacGillivray et al., 1982) except that in the bovine transferrin, Asp is replaced by Asn, enabling carbohydrate attachment. A second glycopeptide sequence Arg‐(CHO)Asn‐Ala‐Thr‐Tyr is observed, and the significance discussed in relation to carbohydrate moieties of serum glycoproteins.