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Biomedical subjects

M V Sidorova

Publications and source records attributed to M V Sidorova.

At least 19 recordsLinked to original sources
PubMed2004

Novel phosphospecific antibodies for monitoring phosphorylation of proteins encoded by the myosin light chain kinase genetic locus.

Myosin light chain kinase (MLCK) and the kinase-related protein (KRP), also known as telokin, are the major independent protein products of the smooth muscle/non-muscle MLCK genetic locus. They share a common C-terminal part and major sites phosphorylated in vivo. Whereas MLCK is critically involved in myosin activation and contraction initiation in smooth muscle, KRP is thought to antagonize MLCK and to exert relaxation activity. Phosphorylation controls the MLCK and KRP activities. We generated two phosphorylation and site-specific antibodies to individually monitor levels of MLCK and KRP phosphorylation on critical sites. We quantified the level of KRP phosphorylation in smooth muscle before and after an increase in intracellular free Ca2+ and stimulation of adenylate cyclase, protein kinase C, and mitogen-activated protein kinases (MAP-kinases). Forskolin and phorbol-12,13-dibutyrate increased KRP phosphorylation at Ser13 from 25 to 100% but did not produce contraction in rat ileum. The level of Ser13 phosphorylation was not altered during Ca2+-dependent contraction evoked by KCl depolarization or carbachol, but subsequently increased to maximum during forskolin-induced relaxation. These data suggest that several intracellular signaling pathways control phosphorylation of KRP on Ser13 in smooth muscle and thus may contribute to relaxation. In contrast, phosphorylation level of Ser19 of KRP increased only slightly (from 30 to 40-45%) and only in response to MAP-kinase activation, arguing against its regulatory function in smooth muscle.

Amino Acid Sequence↗
PubMed2000

Hydrogen peroxide for disulfide bridge formation in methionine-containing peptides.

Two methionine-containing peptides, endothelin 1 and the 1-16 fragment of the receptor of the plasminogen activator 1 for human urokinase, were synthesized and cyclized by hydrogen peroxide. Endothelin 1 was obtained by using regioselective and random schemes of disulfide bond formation. The conditions of cyclization that provided the target products in high purity were found. The general potential of disulfide bond formation by means of hydrogen peroxide was demonstrated for methionine-containing peptides. The method resulted in target products containing insignificant quantities of the corresponding Met-sulfoxide derivatives.

Amino Acid Sequence↗
PubMed1999

[Antibodies against synthetic peptide fragments of T-cadherin inhibit binding of low density proteins with T-cadherin].

Potential antigenic determinants of the atypical lipoprotein-binding proteins T-cadherin (p105) and its precursor (p130) from cells of human smooth muscles were synthesized by the solid phase method according to the Fmoc-scheme. These corresponded to the 51-61, 140-160, 161-179, 260-271, 340-352, 350-362, and 370-385 sequences of p130 and were chosen on the basis of computer analysis of its antigenic structure. The conjugates of the peptides with horseradish peroxidase were used for the immunization of mice and rabbits. Antisera against the peptides corresponding to the 140-160, 161-179, and 260-271 sequences of p105 were shown by immunoblotting to react with p105, which we isolated from the vascular cells of smooth muscles and earlier identified as T-cadherin. These antisera inhibited the binding of low density lipoproteins with p105 in a dose-dependent manner. These results confirmed the identification of the p105 protein as T-cadherin and demonstrated the fundamental possibility of studying the interaction of this protein with low density lipoproteins by using antipeptide antibodies that inhibit binding.

Amino Acid Sequence↗
PubMed1999

[Directed and spontaneous disulfide bond closure using hydrogen peroxide in the synthesis of endothelins-1 and -3].

The linear precursors of endothelin 1 and endothelin 3, natural vasoactive peptides, were obtained by using the Boc- and Fmoc-schemes of solid phase peptide synthesis. The methods of directed and spontaneous formation of two disulfide bonds in the molecules of these precursors were compared and shown to give comparable results. The conditions were found that provided the selective S-S-ring closure in the methionine-containing endothelin 1 by means of hydrogen peroxide without the undesired conversion of the Met residue into the corresponding sulfoxide.

Amino Acid Sequence↗
PubMed1998

Identification of an atypical lipoprotein-binding protein from human aortic smooth muscle as T-cadherin.

We have previously described an atypical lipoprotein-binding protein of about 105 kDa (p105) in membranes of vascular smooth muscle cells (VSMCs) that is distinct from currently known lipoprotein receptors. In the present work we have developed a procedure for purification of p105 from human aortic media. Partial sequencing of purified protein has revealed identity of p105 with human T-cadherin. Anti-peptide antisera raised against human T-cadherin recognized a protein spot corresponding to the purified p105 on two-dimensional Western blots. The antisera also inhibited LDL binding to p105 on ligand blots. We conclude that the 105 kDa lipoprotein-binding protein present in human VSMCs is T-cadherin, an unusual glycosylphosphatidylinositol-anchored member of the cadherin family of cell-cell adhesion proteins.

Amino Acid Sequence↗
PubMed1998

[Synthesis and biological properties of artificial antigens based on 280-289 fragment of beta2-gpI].

A series of artificial antigens were synthesized on the basis of the FC(Acm)KNKEKKC(Acm)S peptide from the beta 2-glycoprotein I sequence: lipophilic analogues, the peptide-BSA conjugate, and multiple antigen peptide (MAP) containing eight copies of the peptide on an oligolysyl core. The solid phase method for acylation of the peptide with fatty acids and the HPLC analysis of the acylpeptides were described. Antigenic properties of the resulting compounds were evaluated by CL-ELISA.

Acylation↗
PubMed1997

Comparative evaluation of different methods for disulfide bond formation in synthesis of the HIV-2 antigenic determinant.

The peptide H-Asn-Ser-Trp-Gly-Cys-Ala-Phe-Arg-Gln-Val-Cys-NHEt corresponding to the 593-603 sequence of gp41 protein of the HIV-2 was used to evaluate different methods for the removal of Acm-protection and subsequent disulfide bond formation. The studied methods involved the treatment by salts of heavy metals (silver and mercury) and subsequent cyclization by oxygen, potassium ferricyanide or hydrogen peroxide. The direct oxidative conversion of Acm-peptide to the corresponding cyclic disulfide by iodine under acidic and neutral conditions was investigated, and the structure of by-products was also studied. The best results were obtained using mercuric acetate followed by oxidation with hydrogen peroxide.

Amino Acid Sequence↗
PubMed1997

[Solid phase synthesis of beta amyloid (1-42)].

A solid phase synthesis of the polypeptide corresponding to the 1-42 sequence of beta-amyloid protein that accumulated in brain cells during Alzheimer's disease was performed using Fmoc strategy. Two alternative approaches to the synthesis, stepwise elongation of the peptide chain and fragment coupling, were compared, and the advantage of the latter approach was shown. Effects of various factors (solvents, reagents for deprotection of alpha-amino functions, and substitution level of polymer carrier) on the synthesis was studied. The appropriate conditions of HPLC for an analysis of the homogeneity of the beta A4(1-42) peptide, as well as the conditions of its gel chromatography on Sephadex G-50 providing the preparation of the end product of 90-95% purity according to HPLC were found.

Amino Acid Sequence↗
PubMed1996

[Hydrogen peroxide for disulfide bridge formation in the synthesis of peptides with the sequence of the immunodominant epitope of HIV gp41 glycoprotein].

A simple, rapid, and highly efficient method for intramolecular disulfide formation in tryptophan-containing peptides using hydrogen peroxide was elaborated. Solid phase synthesis of the peptide fragment corresponding to 601-617 sequence of transmembrane gp41 glycoprotein of HIV-1 was performed by Fmoc-technique. Coupling of Fmoc-Asn-OH by DCC-HOBt method was shown to be accompanied by a side reaction of dehydration of asparagine amide function with the formation of side product (22%) containing 3-cyanoalanine residue. This side reaction was not observed, when Fmoc-Asn-OH was coupled in the form of its p-nitrophenyl ester and with HOBt as a catalyst.

Amino Acid Sequence↗
PubMed1996

[Direct transition of S-acetamidomethyl-protected peptide 593-603 of HIV-2 gp41 into a cyclic disulfide using iodine. Study of side reactions].

Removal of Acm-protecting group from thiol functional groups of Cys residues with simultaneous disulfide bridge formation by iodine in acetic acid was studied in the course of the synthesis of a peptide fragment corresponding to 593-603 sequence of HIV-2 gp41 glycoprotein. The excess iodine influence on the cyclization process was investigated. By-products of the oxidative disulfide formation were isolated, and their structures were elucidated by means of amino acid and elemental analyses, mass spectrometry, NMR, and UV-spectroscopy.

Acetylcysteine↗
PubMed1993

Inhibition of human immunodeficiency virus type 1 (HIV-1) penetration into target cells by synthetic peptides mimicking the N-terminus of the HIV-1 transmembrane glycoprotein.

To investigate the mechanism of action of the 22-amino-acid HIV fusion peptide on HIV infection, we studied its influence on virus adsorption and HIV-induced syncytium formation. The effect of the peptide preparations on the synthesis of viral antigens in HIV-infected cell cultures was determined by antigen capture assay, and the inhibition of proviral DNA synthesis was detected by hybridization with a HIV-specific oligonucleotide probe after PCR amplification. Fusion peptides inhibited HIV-induced syncytium formation and antigen production in lytic infected cells, and this effect was increased in conjugation with bovine serum albumin or with synthetic net-charged polymer by its C-terminus. The association of peptide with carrier by N-terminus, or with positive-charged polymer or gelatin completely abolished its effect on HIV infection. No peptide preparations influenced HIV-1 chronically infected cells. Because peptide preparations blocked the HIV-specific DNA synthesis 2 hr after infection without influencing virus adsorption and reverse transcription, we concluded that the block of infection occurred during the penetration of virions through the cell membrane. On the basis of results obtained we propose that our peptide preparations could be used for anti-HIV chemotherapy. The possibility of the existence of receptors for gp41 N-terminal region on target cell membrane is discussed.

Amino Acid Sequence↗
PubMed1993

[Effect of synthetic fragments of immunodominant regions of HIV viral proteins on the oxygen metabolism of human neutrophils].

Influence of synthetic peptides identical to fragments of natural human immunodeficiency virus (HIV) glycoproteins gp 120 and gp 41, on luminol-enhanced chemiluminescence (CL) of human neutrophils has been studied. It was established that some of peptide analogs of gp 120 and gp 41 immunodominant regions are able to suppress spontaneous CL: but when being used with dimethylsulfoxide they dramatically stimulate it and deteriorate opsonized zymosan-induced CL. Conclusions about the necessity of possible side effects considering during use of peptide vaccines against HIV have been made. It is also possible to explain some neutrophil dysfunction in HIV infected subjects as the result of HIV glycoproteins direct influence on this cells.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Investigation of human immunodeficiency virus fusion peptides. Analysis of interrelations between their structure and function.

The N-terminal region of the human immunodeficiency virus type 1 (HIV-1) gp41 appears to be involved in virus-cell membrane fusion. To study the influence of fusion domain structure on gp41 interaction with artificial lipid membranes, two families of peptides were synthesized. The peptides of the first family starting from the C-terminal Gly-532 of gp160 (BRU isolate) were assembled in a stepwise manner to N-terminus of gp41(Ala-517). These hydrophobic peptides, containing 10-16 amino acid residues (a.a.), were able to form channel-like current fluctuation through planar lipid membranes, and the longest 15-16 a.a. peptides lysed the liposomes. Peptides of the second family beginning from the C-terminal Arg-538 and continuing to Val-510 contained several hydrophilic amino acid residues. These 15-22 a.a. peptides also increased the conductance of planar lipid bilayers and lysed liposomes. The degree of liposome lysis depended upon peptide length and concentration. The attachment of gp120 C-terminal amino acid or peptides to N-terminus of 517-538 peptide resulted in complete loss of activity. The effects of the second family of peptides on membranes were reduced to a great extent at acidic pH. The conjugation of 22 a.a. Lys peptide with bovine serum albumin decreased its lytic activity. The circular dichroism study of these peptides revealed alpha-helix configuration in hydrophobic and aqueous media only for deca- and longer peptides. The electron microscopy of 22 a.a. peptide performed in the aqueous medium showed large spherical aggregates about 0.5-0.7 micron in diameter consisting of long filaments approximately 5 nm in diameter. Other tested peptides could generate only short strings. Thus, the effects of fusion peptides on lipid membranes depends on their sequence and length, secondary and tertiary structures, and freedom of their N-terminus.

Amino Acid Sequence↗
PubMed1992

[Peptides from the principal neutralizing and CD4-binding domain: similar immunoreactive properties and structure pattern].

The human immunodeficiency virus (HIV) proteins gp120 and gp41 are the principal immune target in HIV infection. One of the most important trends in the study of AIDS is linked to the mapping of sites involving in the binding to the cell receptor CD4 and in the induction of virus-neutralizing antibodies (VNA). Recent studies have revealed that gp120 as the major domain contains inducing type-specific BNA (PND) and a binding region with CD4 (CD4-BR). PND is located in the hypervariable loop of gp120 (residues 301-336 for a BRU strain), and CD4-BR is in the conservation area (residues 410-450). By using the synthetic fragments from these areas (BRU and MN strains) and HIV-infected persons' sera, the authors established that the immune response to PND and CD4-BR is somewhat interrelated: there is a synchronized response of HIV antibodies to peptides from the two regions in ELISA (r = 0.82). For analysis of this phenomenon, experiments with cross-linked immunoreactivity of rabbit antisera to peptides from PND and CD4-BR with homologous and heterologous peptides were performed by applying three control peptides from HIV and hepatitis B virus. It has been found that there is a cross reactivity between rabbit anti-PND (MN, BRU) and anti-CD4-BR abs. Peptide homological analysis revealed common structural elements for PND and CD4-BR despite significant differences in their proposed functions. There is a large amount of positively charged aa within both PND and CD4-BR which may be involved in gp120-CD4 interaction. Acetylation of Lys residues resulted in complete loss of peptide reactivity.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Analysis of the fine structure of the antigenic determinants of the transmembrane protein in the HIV coat with chemically modified synthetic peptides.

The amino acids involved in IgG reactivity to four HIV-1 gp41 overlapping synthetic peptides from the sequence 584-624 have been determined by a method based on the chemical modification of trifunctional amino acids, especially the acetylation of the amino groups of the lysine residues at pH 8-9. The reactivities of the sera from HIV-infected individuals and gp41-specific human Mab were studied with the overlapping peptides and their modified forms in indirect and competitive ELISA. Peptides 584-602 and 609-624 (CN-185) reacted with 88% of HIV-positive sera; the highest diagnostic significance (100%) was found with peptides 584-611 (AS-551) and 603-624 (CN-191). Acetylation resulted in a 10%-15% decrease in peptide reactivity. Moreover the concentration at which 50% inhibition occurred was 1.5 x 10(-6) M for unmodified AS-551 compared with 1.5 x 10(-5) M for the modified peptide. Circular dichroism spectra showed that acetylation did not alter the conformation of these peptides. Coupling of peptide AS-551 to a protein carrier at pH 6.5-7.0 did not affect the immunoreactivity of this peptide. Mab against human gp41 reacted with peptide 603-624 (CN-191). The concentration of this peptide necessary for 50% inhibition of Mab binding was 5.2 x 10(-6) M. It is concluded from the epitope mapping of the Mab that the antigenic determinant lies within the 603-609 fragment. Lys-608 appears to play a crucial role in the interaction with human HIVc-Mab.

Amino Acid Sequence↗