[Synthesis of poly (Lys-Ser-Glu) and study of its antigenic and immunogenic properties]

We have synthesized oligo- and polypeptides containing lysin, serine and glutamic acid residues. Di- and tripeptides were prepared by the successive elongation of C-terminus by means of the N,N'-dicyclohexylcarbodiimide or mixed anhydride methods. The oligopeptides were obtained by block condensation of pentafluorophenyl esters of tripeptides, and polypeptides by polycondensation of dipeptide 2,4,5-trichlorophenyl esters. The three amino acids (Lys, Ser, Glu) were shown to take part in formation of antigenic determinants, serine being probably the immunodominant amino acid, and dipeptide Ser-Glu- the most important component of the epitope Lys-Ser-Glu. Polypeptides (Lys-Ser-Glu)n induced cross-reacting or heteroclitic antibodies. The expression of immune response depended on genotype of experimental animals.