[Myelopeptide MP-5 and fluorescent derivatives: synthesis and biological activity].

The Val-Val-Tyr-Pro-Asp bone marrow peptide (MP-5) and an analogue (MP-5-Lys) were synthesized. Fluorescent derivatives, Ftc-MP-5 and MP-5-Lys(Ftc), were prepared. The biological activity of MP-5 and MP-5-Lys was studied in vitro and in vivo.

[Fluorescently labeled differentiating myelopeptide-4: specific binding to and penetration into target cells].

Myelopeptide-4 (MP-4) (Phe-Arg-Pro-Arg-Ile-Met-Thr-Pro), inducing the terminal differentiation of HL-60 leukemia cells, was labeled with fluorescein isothiocyanate. The specific binding of this modified peptide to the surface of HL-60 cells and its ability to penetrate into the cells were studied. It was shown by cytometry and confocal microscopy to be bound on the HL-60 cell surface, to penetrate into their cytoplasm, and finally to concentrate around the cell nucleus.

[Synthesis and properties of the retro-analogue of myelopeptide MP-2].

The bone marrow myelopeptide MP-2 (Leu-Val-Val-Tyr-Pro-Trp), exhibiting antitumor activity, and its retro-analogue (Trp-Pro-Tyr-Val-Val-Leu) were synthesized, and their properties were studied. The in vitro and in vivo activities of retro-MP-2 were comparable with those of MP-2. Both peptides equally restored the functional activity of T-lymphocytes inhibited by toxins released by HL-60 cells and inhibited by 70-82% the growth of various types of transplantable solid tumors: Ca-755 adenocarcinoma of the mammary gland, Lewis adenocarcinoma of the lung, and S180 sarcoma.

[Effect of the SH-group of myelopeptide MP-3 on its macrophage-stimulating activity].

Peptide Leu-Val-Cys-Tyr-Pro-Gln, identical to the bone marrow peptide MP-3, and its Val3 and Ser3 analogs, lacking SH-group, were synthesized by conventional methods of peptide chemistry in solution and, along with the MP-3 S-S-dimerization product, were studied with respect to their effect on the macrophage phagocytic activity. It was shown that the activity was only enhanced by peptide MP-3, which demonstrated the essential role of the SH-group in this function. The dimer analog of MP-3, unlike dimer analogs of other monocysteine-containing peptides, glutathione and HP5b, did not exhibit the inhibitory effect.