Isolation and Characterization of CNBr Derived Peptides of the α1 (III) Chain of Pepsin-Solubilized Calf Skin Collagen

Fetal calf skin was solubilized by limited pepsin digestion and type III collagen separated from type I collagen by fractional salt precipitations. Cleavage of the type III collagen with CNBr gave rise to ten peptides, which were isolated by molecular sieve and ion exchange chromatography. The peptides were characterized by determination of their molecular weights and amino acid compositions. Together they account for all the amino acids and total molecular weight of the alpha1 (III) chain. Six of the peptides contain more hydroxyproline than proline residues. The two cysteinyl residues of the alpha1 (III) chain which provide sites for interchain disulfide bonding were localized in the C-terminal CNBr peptide. In addition to the ten CNBr peptides, three double peptides were isolated which still contained one methionine residue. About 0.1 residue Gal-Hyl monosaccharide and 0.8 Glc-Gal-Hyl residue disaccharide were found per alpha1 (III) chain. Almost all hydroxylysine-bound carbohydrate was located on peptide 7.