During our work on the periodicity of the genetic code we proposed a new scheme of amino acid pairing [Siemion, I.Z. and Stefanowicz, P., Biosystems, 27 (1992) 77; Bull. Pol. Acad. Sci., 40 (1992) 11]. Based on this scheme, we designed and synthesized the sequences IIYTLC(Acm)GLYL (II), IIYPLC(Acm)GLYL (V), and IYPLC(Acm)GLY (VI), which are ‘antipeptides’ with respect to immunoactive fragments of TGFβ2: YIGKTPKI (III) and YYIGKTPKIE (IV). The peptide–antipeptide interaction was investigated by electrospray ionization mass spectrometry and circular dichroism methods. The results obtained indicate that peptides interact selectively with ‘antipeptides’.