The cyanogen bromide peptides of bovine soluble and insoluble collagens: I. Characterization of peptides from soluble type I collagen by sodium dodecylsulphate polyacrylamide gel electrophoresis

Acid soluble collagen and purified al and α2 chains were prepared from bovine skin and digested with cyanogen bromide. The resultant peptides were separated by electrophoresis on polyacrylamide gels containing sodium dodecylsulphate. Thirteen peptides obtained from the al chain and two from the α2 chain were identified as overlapping sequences containing methionine-derived peptide bonds not cleaved during the reaction. Those uncleaved peptides from the al chain accounted for approximately 30% of the total digest, as determined by planimetry on the staining profiles, and their relative proportions indicated that efficiency of cleavage at specific methionine residues was dependent upon position in the sequence. α1CB5-8 was most resistant to cleavage while α1CB0, 1-2 and α1CB7-6 were most susceptible. Peptides of a 2:1 (w/w) mixture of α1 and α2 chains and of the acid-soluble collagen gave electrophoretograms which were essentially a summation of those obtained from the individual chains.