Immunochemical studies with synthetic peptides related to collagen

We have previously reported that the synthetic octapeptide having the amino acid sequence Gly-Pro-Gly-Pro-Pro-Gly-Ala-Lys exhibited immunological properties related to those of collagen and gelatin. The present communication reports on the specificity of rabbit antibodies to the octapeptide, elicited in response to immunization with the octapeptide conjugated to succinylated bovine serum albumin. Investigations on the reactivity of these antibodies with shorter C-terminal peptides, and on the capacity of C-terminal peptides to inhibit the reaction between the antibodies and the octapeptide revealed that the antigenic specificity of the octapeptide resides in its C-terminal pentapeptide having the amino acid sequence Pro-Pro-Gly-Ala-Lys. The capacity of the ordered polymer (Pro-Gly-Pro)_n (mol. wt 1910) to inhibit the above reaction suggests that the antigenic specificity of the octapeptide is dependent upon the sequence Pro-Pro-Gly. In addition, the investigations revealed immunological cross reactivity between the octapeptide and collagens and/or gelatins derived from several animal species including humans.