Aleksandra Kubik

Immunoregulatory properties of synthetic peptides, fragments of a proline-rich polypeptide (PRP) from ovine colostrum

It has been previously found that a proline-rich polypeptide (PRP) isolated from ovine colostrum has a regulatory effect on the immune response. A nonapeptide fragment Val-Glu-Ser-Tyr-Val-Pro-Leu-Phe-Pro was isolated from the chymotryptic digest of PRP. The nonapeptide showed biological activity similar to PRP. The determined amino acid sequence was now confirmed by synthesis. Synthetic nonapeptide as well as its C-terminal hexapeptide, Tyr-Val-Pro-Leu-Phe-Pro, showed biological activity similar to PRP and the nonapeptide obtained from PRP.

Immunoregulatory activity of substance P fragments

The C-terminal SP7-11 pentapeptide (Phe-Phe-Gly-Leu-Met-NH2) was found to suppress in vitro the immune response in a dose of 1-5 micrograms/ml. It produced also a distinct immunosuppression in vivo, by both per os and intraperitoneal, applications. In contrast, the N-terminal SP1-4 fragment (Arg-Pro-Lys-Pro) suppressed the response at a dose of 0.1 microgram/ml, but stimulated it slightly at higher doses (1-5 micrograms/ml). A structural analog of SP1-4 (Gly-Pro-Arg-Pro tetrapeptide) was found to be a strong immunosuppressor at a dose of 5 micrograms/ml, indicating the importance of N-terminal basic residue for the immunoregulatory activity of intact SP.

The absolute configuration on the chiral nitrogen atom of proline residue in the metal complexes of oligopeptides

The CD spectra of the Cu(II) and Ni(II) complexes with peptides containing N-terminal L-proline residue are discussed. The formation of the absolute configuration on the bound proline nitrogen is observed in all studied complexes and its contribution to the chiralooptical properties is easily seen in CD spectra.

New analogs of the immunoregulatory PRP-pentapeptide

To determine the role of consecutive amino acid residues in the immunoreactivity of the shortest active fragment of PRP, a series of analogs substituted by L-alanine in successive positions of the peptide chain was synthesized. The immunological investigations were carried out in several models: the immune response to T-cell dependent antigen, SRBC (in vivo and in vitro) and to T-cell independent antigen, PVP in vitro. The immunotropic action of the peptide was, in addition, verified with respect to thymocytes forming autologous rosettes. The results of these experiments revealed immunotropic activity (in all tests) of the analog containing alanine instead of proline in position 5 of PRP-pentapeptide.

Synthesis of the Gln1-facteur thymique serique and its evaluation with human E-rosette bioassay

Abstract Synthesis of an analog of facteur thymique serique (FTS) containing a glutaminyl residue in position 1 of the peptide chain is described. Like the original FTS, Gln 1 -FTS is able to induce T cell markers on lymphocytes in vitro in a picogram dosage range. The human E-rosette bioassay was adopted for the evaluation of biological activity of Gln 1 -FTS. It was also shown that the latter method can be used to evaluate the presence of target cells for FTS activity in peripheral blood lymphocytes in humans.