CHARACTERIZATION OF CYANOGEN BROMIDE PEPTIDES FROM ALPHA1 CHAIN OF CHICK SKIN COLLAGEN

The α1 chain of chick skin collagen was cleaved at the methionyl residues with cyanogen bromide and the resulting peptides were separated and characterized. Ten peptides of varying molecular weight ranging from 242 to 25,000 were obtained. The sum of the molecular weights of these peptides as determined by gel filtration was 91,567, and that determined by amino acid analysis was 90,721, values which are in good agreement with the known molecular weight of the α1 chain. The sum of the amino acid compositions also agrees with the composition of the whole α1 chain. These data indicate that the ten peptides account for the entire amino acid sequence represented in the original α1 chain. The finding of only ten unique peptides from a chain containing nine methionyl residues indicates that the two α1 chains of chick skin collagen are identical or very similar in their amino acid sequence. These peptides are similar and clearly homologous to the cyanogen bromide peptides previously isolated from the α1 chain of rat skin collagen. They are identical in every respect examined with the cyanogen bromide peptides from the α1 chain of chick bone collagen except for the degree of hydroxylation of lysine. This result suggests that chick bone and skin collagens are derived from the same structural genes and, therefore, that the different properties of the two tissues cannot be explained on this basis. © 1969, American Chemical Society. All rights reserved.