Immunosuppressive activity of analogs of tripeptide Lys-Arg-Pro with D-amino acid residues.

Synthesis of four analogs, containing D-amino acid residues, of the tripeptide immunosuppressor Lys-Arg-Pro is described. In addition, acetyl and amide derivatives of this peptide were synthesized. Biological effects of all peptides were studied using a delayed type hypersensitivity (DTH) test. It was found that incorporation of D-amino acid residues in definite positions of the peptide chain gives the substances with immunosuppressive activity. A strong immunosuppressive activity was observed also for all-D-analogs (D-Lys-D-Arg-D-Pro).