[The effect of modified forms of vasopressin on the rat hemostatic system].

The effect of modified forms of vasopressin (MFV) that do not possess hormonal activity on homeostasis in rats was studied. One of the major effects of vasopressin (AVP) and its analogs on the blood clotting system, changes in fibrinolytic activity (FA) and the activity of plasminogen activator (APA), depends on modifications of the amino acid sequence in the peptide molecule. The presence of glycinamide in the AVP molecule enhances FA and APA.

[Structural and functional analysis of the human immunodeficiency glycoprotein gp120 with homologous synthetic peptides].

The purpose of the study was to identify sites of gp 120, which are responsible for CD4 binding and induce tumor necrosis factor-alpha (TNF-alpha) synthesis. Seven peptides were synthesized from gp 120. The peptides were studied in the following biological tests: binding to CD4 molecules of the Jurkat cell clones 3G6 and PBMC of healthy persons.

The sequence 130-137 of human interferon-alpha 2 is involved in the competition of interferon, prothymosin alpha and cholera toxin B subunit for common receptors on human fibroblasts.

125I-labelled recombinant human interferon alpha 2 (rHuIFN-alpha 2) capable of high-affinity binding (Kd = 2.46 +/- 0.18 x 10(-10) M) with receptors expressed on mouse thymocytes was obtained.

[Conformational analysis and hemolytic activity of immunoglobulin G fragment 285-292 and its analogs].

Theoretical conformational analysis was carried out for the 285-292 fragment of human immunoglobulin G (His-Asn-Ala-Lys-Thr-Lys-Pro-Arg) and its analogues containing Arg, Glu, Gly, Lys, or Trp residue instead of the His residue in position 1. Spectropolarimetic investigation of these peptides showed the analogues to have different activities in the C1q-mediated erythrocytes hemolysis assay. Comparison of the low-energy structures sets of the compounds tested allowed to suggest a model of the "biological active" conformation for the peptide molecule in the course of the C1q complement component binding.

Nonapeptide corresponding to the sequence 27-35 of the mature human IL-2 efficiently competes with rIL-2 for binding to thymocyte receptors [corrected].

Previously it was shown [1] that amino acid substitutions at the region of the first alpha-helix of IL-2 specifically inactivate its reactivity with the intermediate-affinity receptor p70, and mutations in the fifth alpha-helix specifically inactivate the binding to the low-affinity receptor p55. We have synthesized the peptides corresponding to the putative binding site of IL-2 with the intermediate-affinity receptor p70 and found that the nonapeptide corresponding to the sequence 27-35 of the mature IL-2 [2] effectively competes with human rIL-2 for binding to thymocyte receptors. Two types of nonapeptide receptors were revealed: those with Kd1 = 1.