Analysis of an evolutionarily conserved antigenic site on mammalian cytochrome c using synthetic peptides.

Two synthetic peptides inclusive of the NH2-terminal N-acetyl-Gly-Asp-Val-Glu tetrapeptide of mammalian cytochrome c (cyt c) were used in this study to address the question of whether mammals can respond immunologically to an evolutionarily conserved region of a protein. These peptides were assessed for their capacity (i) to act as immunogens for the production of anti-self cyt c antisera and (ii) to bind rabbit anti-rodent cyt c antibody. The findings from these studies indicate the existence of an immunogenic determinant in an evolutionarily conserved region of cyt c that contains residues 1-4. This determinant can induce anti-self cyt c antibodies whether presented as a peptide on a carrier protein or in the context of the intact molecule as polymerized mammalian cyt c.