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Biomedical subjects

V T Ivanov

Publications and source records attributed to V T Ivanov.

At least 91 records · Page 5Linked to original sources
PubMed1991

[Use of synthetic carriers and adjuvants for increasing the immunogenicity of a synthetic peptide from the CS-protein of Plasmodium falciparum].

In order to increase immunogenicity of the peptide (NANP)3, we have prepared a large set of fully synthetic constructions based on the peptide, glycopeptide adjuvant GMDP and some synthetic carriers. Immunogenicity of these constructions was tested on mice (line C57B1/6) responding to the peptide polymer (NANP)40 without carrier and on mice (line BALB/c) not responding to this antigen. Immunogenic constructions based on synthetic polytuftsin induced as high titres of anti-(NANP)3 antibodies as the standard conjugate KLH--(NANP)3. The chimeric peptide consisting of (NANP)3 and tuftsin dimer induced anti-(NANP)3 antibodies in both lines of mice as well. The GMDP covalent attachment to the immunogenic constructions increased the antipeptide antibodies titre. The results are discussed in terms of an approach to synthetic vaccines.

Amino Acid Sequence↗
PubMed1991

[Synthesis and immunochemical properties of oligopeptides--fragments of capsid proteins of the hepatitis A virus].

The hepatitis A virus (HAV) capsid protein VP1, VP2 and VP3 are exposed at the virion surface and should therefore contain antigenic determinants. Algorithms for hydrophilicity, antigenicity and flexibility were used to predict probable antigenic sites. Synthesis of 7- to 23-membered overlapping peptides from seven sites, viz., 1-11, 1-17, 2-33, 11-25, 73-82, 76-86, 98-109, 98-112, 102-107, 102-108, 108-127, 113-123, 118-140, 276-298 from VP1, 42-62 from VP2, 76-85 from VP3, and 1-23 from VP4, was performed by various solid-phase methods. Free peptides and their conjugates with different carriers were used for immunization and study of antigenicity. The peptides did not interact with antibodies to the hepatitis A virus, whereas their conjugates did not induce the formation of anti-HAV-antibodies.

Amino Acid Sequence↗
PubMed1991

[Structure-functional study of glycosaminylmuramoyl peptides. The effect of chemical modification of N-acetylglucosaminyl-N-acetylmuramoyldipeptide on its immunomodulating properties in vivo and in vitro].

The structure-function relationships in a series of synthetic glucosaminylmuramyl peptides--glycopeptide adjuvants of the bacterial origin--have been investigated. Modification of the N-acetylglucosaminyl-(beta 1-4)-N-acetylmuramyl-L-alanyl-D-isoglutamine (GMDP) molecule affects its adjuvant and pyrogenic activity in vivo. GMDP is shown to readily stimulate the synthesis of the IgG2a and IgG3 of the immunoglobulin subclasses upon the secondary immune response to the protein antigen. The adjuvant effect correlates with the comitogenic test of the reaction of splenocytes blast-transformation in the presence of B-cell mitogen. No direct dependence has been revealed between the level of the glycopeptides adjuvant action and their effect on the IL-1 production by macrophages.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1991

[Study of the interaction of the monoclonal antibody to human interleukin-2 and its Fab-fragment with synthetic peptides --interleukin-2 fragments by (1)H-NMR].

Proton signals for nine synthetic peptide fragments of human interleukin-2 (region 59-78) were assigned for aqueous solutions both of pure peptides and their mixtures with LNKB-2 monoclonal antibody. The nonspecific magnetization transfer (NOE) between the antibody or its Fab-fragment and the peptides was studied upon large excess of free peptide over bound peptide. NOE spectra using modified pulse sequence, enabling to eliminate broad signals and achieve higher (peptide signal)/noise ratio were obtained. The saturation transfer experiments indicated that methyl groups of amino acid residues corresponding to Leu66,70,72, Val69 and Ala73 in interleukin-2 contact with the antibody binding site. Thus, the hydrophobic interactions are of major importance for the LNKB-2-IL-2 peptide complexes. The minimal IL-2 fragment which can still bind to LNKB-2 monoclonal antibody is -Leu70-Asn71-Leu72-.

Amino Acid Sequence↗
PubMed1991

Study of immunomodulatory properties of N-acetylmuramyl-L-alanyl-D-isoglutamine and N-acetylglucosaminyl-(beta 1----4)-N-acetylmuramyl-L-alanyl-D-isoglutamine.

The immunomodulatory activities of two synthetic muramylpeptides (MP), a muramyl dipeptide and a glucosaminyl-muramyl dipeptide, have been compared and have been found to exhibit many common features in their effects. In addition, the differential effects of low and high concentrations of MP on the primary humoral immune response in vitro were examined in detail. At high concentrations MP augmented the frequency of induced T-suppressor cells, while at low concentrations the primary immune response was stimulated by enhancement of the antigen-presenting function of accessory cells and by increasing the frequency of induced T-helper cells.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1991

[Crystallization and molecular structure of cyclic dodecadepsipeptide cyclo]D-Val-D-Hyi-Val-Hyi-(D-Val-Hyi-Val-D-Hyi)2-].2C3H60].

The crystal structure of a synthetic analogue of meso-valinomycin, crystallized with two acetone molecules, has been solved by X-ray direct methods. The trigonal crystals belong to the P32 space group, with the number of molecules in the unit cell z = 3, and cell dimensions a = b = 15,2085 A, c = 29,3250 A, alpha = beta = 90 degrees, gamma = 120 degrees. The standard (R) and weighted (Rw) factors after the structure refinement of atoms C, N, O in anisotropic thermal motion approximation and with the contribution from H atoms taken into account are 0,070 and 0,082, respectively. The molecule adopts an asymmetric conformations stabilized by six amide intramolecular hydrogen bonds NH ... OC of the 4----4 type; one of those is strong and the other are weakened in different extent. The side chains occupy the external pseudoaxial positions towards the cyclic frame of the molecule, whereas six free ester carbonyl groups have different orientations. In contrast to meso-valinomycin, the analogue under study has no specific binding site for metal ions. The isopropyl side chains of D-Hyi(2) and Hyi(4) residues effectively shield, from both sides, the access to the inner molecular cavity.

Amino Acid Sequence↗
PubMed1990

Lassa virus glycoproteins: antigenic and immunogenic properties of synthetic peptides to GP1.

Synthetic peptides corresponding to predicted Lassa virus GP1 glycoprotein B-epitopes were used to study the antigenicity and immunogenicity of the protein. ELISA results showed that guinea pig polyclonal anti-Lassa virus serum bound effectively to peptides corresponding to amino acid residues 119-133 and 164-176 of the GP1 protein. Essentially it did not react to a peptide corresponding to GP1 amino acid residues 234-256. Sera obtained against peptides representing amino acid residues 119-133 and 164-176 reacted with inactivated purified Lassa virus.

Amino Acid Sequence↗
PubMed1990

Muramylpeptides augment expression of Ia-antigens on mouse macrophages.

The muramylpeptide N-acetylglucosaminyl-beta 1----4-N-acetylmuramyl-L-alanyl-D-isoglutamine (GMDP) was shown by flow cytometry to produce a dose-dependent increase in the expression of Ia-antigens by mouse peritoneal macrophages in vitro. Muramyldipeptide (N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) had a similar, but weaker, effect. GMDP also induced expression of Ia-antigens by murine peritoneal macrophages in vivo. GMDP acted directly on the macrophages because Ia-antigen expression by cells of the cloned mouse myelomonocytic line WEHI-3 was also induced. Expression of the interleukin-2 receptor on the surface of the macrophages was also stimulated by GMDP, indicating that GMDP may influence development of the immune response through this mechanism.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1990

[Synthetic immunogenic complexes containing a peptide from the surface protein of the foot-and-mouth disease virus].

Synthetic constructions containing a peptide antigenic determinant (C-terminal peptide 205-213 of the surface VP1 protein of the foot-and-mouth disease virus, O1K strain), glucosaminylmuramayl dipeptide (GMDP), and polyionic synthetic carriers were prepared. The polymerized peptide and peptide-BSA conjugates were synthesized as well. Among the constructions obtained only peptide-BSA conjugate proved to be highly immunogenic. Application of synthetic constructions to design immunogenic complexes is discussed.

Amino Acid Sequence↗
PubMed1989

Muramyl peptides bind specifically to rat brain membranes.

The capability of immunoactive muramyl peptides to bind specifically to rat brain membranes has been discovered. The reaction of an N-acetylglucosaminylmuramyl dipeptide analog having an additional C-terminal lysine residue (GMDP-Lys) with Bolton-Hunter reagent or N-hydroxysuccinimidyl-4-azidosalicylate afforded two acylated derivatives, GMDP-Lys-(Hp) and GMDP-Lys(Azs). Their iodination resulted in radioactive derivatives (spec. act. approximately 2000 Ci/mmol) whose binding to rat brain membranes is characterized by Kd approximately 3 nM and Bmax approximately 10 fmol/mg membrane protein. Binding could be inhibited by muramyl dipeptide (MDP), GMDP-Lys, and GMDP, while fragments of the latter, N-acetylglucosamine dipeptide and disaccharide, were ineffective.

Acetylation↗
PubMed1989

Glucosaminylmuramyl dipeptide-induced changes in murine macrophage metabolism.

The purpose of the study was to investigate influence of glucosaminyl muramyl dipeptide (GMDP) and its derivatives on adenosine deaminase (ADA, CE 3.5.4.4.) and 5'-nucleotidase (5-N, CE 3.1.3.5) activity in murine macrophages in vitro. The intensity of superoxide radicals (O2-) formation by these cells has been also studied. GMDP incubated with macrophages was found to inhibit substantially the activity of 5-N, without affecting the activity of ADA in these cells. The maximal effect on 5-N activity was noted following 24 h of co-culture and was accompanied by a higher intensity of O2- formation. GMDP added in doses ranging from 0.01 to 1 microgram/ml induced a gradual decrease in 5-N activity, with an increase in activity of the O2- -generating system. The GMDP analog with double dipeptide link GM(DP)2 has demonstrated the same activating effect as GMDP. The presence of dipeptide alanyl-D-isoglutamine in the GMDP structure is necessary for realization of the drug activating effect, as N-acetylglucosaminyl-N-acetylmuramyl failed to influence macrophage activity. Neither D-D nor L-L isomers of the drug affect the 5-N activity and O2- formation in macrophages. The mechanism of macrophages activation induced by GMDP may include the inhibition of 5-N activity and the stimulation in production of superoxide radicals.

5'-Nucleotidase↗
PubMed1989

Molecular conformation and ion transport of cyclic and linear ionophores.

X-ray crystal structure determinations and energy-minimization techniques provide conformational data on the complexed and uncomplexed forms of ion transport antibiotics of the shuttle and channel types. In the solid state, hexadecaisoleucinomycin (HEXIL), an analogue of valinomycin, is observed as an asymmetric macrocycle stabilized by eight intramolecular (4----1) hydrogen bonds. The structure obtained from energy-minimization procedures exhibits a greater variation in phi and psi angles of chemically equivalent residues than does the crystallographically observed structure. The structure has eight carbonyl groups directed toward its interior and is capable of providing flexible coordination to a positively charged ion or molecule. These structural findings are consistent with the observed capacity of HEXIL to complex cesium ions, tetramethyl ammonium ions and acetylcholine. Gramicidin A is a pentadecapeptide that functions as a transmembrane channel for transporting monovalent cations. Uncomplexed gramicidin A crystallizes as a left-handed, antiparallel, double-stranded, helical dimer with 5.6 amino acid residues per turn. The helix has an overall length of 31 A and an average inner channel diameter of 4.8 A. The channel of this crystalline form does not contain ions or solvent molecules. Transporting ions through this channel could be achieved only by some expansion of the channel opening that would involve breaking and reforming hydrogen bonds that stabilize the double-stranded helix.

Gramicidin↗
PubMed1989

[Antigenic structure of the foot-and-mouth disease virus. III. Immunogenic properties of synthetic peptides of the sequence of the immunodominant region of VP1 proteins of the O1K and A22 strains of foot-and-mouth virus].

Immunogenic and protective properties of uncoupled and KLH-conjugated peptides covering the sequence of the immunodominant region of VP1 proteins of the O1K and A22 strains of foot-and-mouth disease virus have been studied. The uncoupled peptides 136-148 O1K, 136-152 O1K, 131-149 A22 and 140-149 A22 were shown to be immunogenic in guinea pigs and induced 50-100% protection against homologous virus. On the other hand, the A22 specific peptides, in contrast to the O1K peptides, were not immunogenic in rabbits. Immunization of nonresponders with the A22 specific peptides containing the O1K peptide can bypass nonresponsiveness to the A22 peptide in terms of the antibody production. The induced antibodies showed virus-neutralizing activity in vitro.

Amino Acid Sequence↗
PubMed1989

[Antigenic structure of foot-and-mouth virus. IV. Synthesis and immunogenic properties of new fragments of the VP1 protein of food-and-mouth virus strain A22].

A synthesis of new fragments of VP1 protein with the specificity of A22 strain of foot-and-mouth disease virus is described. Immunization with the free 136-152 peptide and KLH-conjugates of the peptides 136-152 and 197-213 induced 60-80% protection of guinea pigs against challenge with the A22 virus. Synthetic peptides corresponding to the 10-24, 50-69 and 175-189 sequences of VP1 did not show any protective activity. We have found that uncoupled peptides 175-189 and 197-213 are able to induce antipeptide antibodies. However, these antibodies did not possess any neutralizing activity. Immunization of animals with the mixture of (136-152)O1K and (175-189)A22 has led to inhibition of the immune response to the (136-152)O1K fragment.

Amino Acid Sequence↗