Publications by authors named "Efimov S"

The spectral characteristics of cyclosporin C (CsC) with the addition of Dy ions in acetonitrile (CDCN) and CsC with Dy incorporated into dodecylphosphocholine (DPC) micelle in deuterated water were investigated by high-resolution NMR spectroscopy. The study was focused on the interaction between Dy ions and CsC molecules in different environments. Using a combination of one-dimensional and two-dimensional NMR techniques, we obtained information on the spatial features of the peptide molecule and the interaction between CsC and the metal ion.

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We have studied the effect of calcium ions (Ca) at various concentrations on the structure of lipid vesicles in the presence of amyloid-beta peptide Aβ(25-35). In particular, we have investigated the influence of calcium ions on the formation of recently documented bicelle-like structures (BLSs) emerged as a result of Aβ(25-35) triggered membrane disintegration. First, we have shown by using small-angle X-ray and neutron scattering that peptide molecules rigidify the lipid bilayer of gel phase DPPC unilamellar vesicles (ULVs), while addition of the calcium ions to the system hinders this effect of Aβ(25-35).

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Cyclosporin is an 11-amino acid cyclic peptide with pharmacologically valuable properties which has a variety of actual and potential applications. Its activity relies on the cell membrane permeability which, in turn, depends on the structure of cyclosporin and its ability to change the conformation. In this work, conformational exchange processes occurring in cyclosporin C were studied using one- and two-dimensional nuclear magnetic resonance spectroscopy.

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Our complementary experimental data and molecular dynamics (MD) simulations results reveal the structure of previously observed lipid bicelle-like structures (BLSs) formed in the presence of amyloid-beta peptide Aβ(25-35) below the main phase transition temperature (T) of saturated phosphatidylcholine lipids and small unilamellar vesicles (SUVs) above this temperature. First, we show by using solid-state P nuclear magnetic resonance (NMR) spectroscopy that our BLSs being in the lipid gel phase demonstrate magnetic alignment along the magnetic field of NMR spectrometer and undergo a transition to SUVs in the lipid fluid phase when heated through the T. Secondly, thanks to the BLS alignment we present their lipid structure.

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  • A new method for synthesizing pyrazolo[3,4-]pyridines is introduced, using 3-arylidene-1-pyrrolines and aminopyrazoles in a single reaction process.
  • The reaction involves a series of steps: nucleophilic addition, electrophilic substitution, and C-N bond cleavage, resulting in derivatives with a primary amino group.
  • This method allows researchers to stop the reaction at the electrophilic substitution phase, offering an easier way to create the challenging pyrazolopyrrolopyridine structure.
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  • Researchers created two types of polysiloxanes (cubic and linear) with branches made of polyoxyethylene using specific chemicals, finding that these new materials don't easily self-condense.* -
  • A detailed study showed how varying the amount of copper chloride affects the structure of these polysiloxanes and their ability to improve the absorption characteristics of certain membranes made from block copolymers.* -
  • The developed membranes demonstrated increased sorption capacity and high permeability for organic dyes and metal ions, which linked their internal structures to successful chemical reactions involving an analytical reagent (PAN) and copper chloride.*
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  • Peptides, like cyclosporins, are essential for various biological activities, and their functions can be influenced by how easily they pass through cell membranes.
  • Molecular dynamics simulations and NMR spectroscopy were used to study cyclosporins C, E, H, and L, revealing similarities in their spatial structures and changes when interacting with lipid bilayers.
  • Understanding how these peptides interact with model membranes can provide insights into their membrane permeability, which is crucial for their biological effects.
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  • * The study analyzed Arbidol’s conformational preferences in different solvents (deuterated chloroform and dimethyl sulfoxide) at 25 °C using the 2D NOESY method, highlighting its various solvate forms based on molecular conformation.
  • * The combination of NMR and X-ray data determined the conformer populations of Arbidol in the two solvents, revealing that the preferred conformation in solution corresponds to the stable crystal solvates of the compound.
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  • Researchers developed polyurethane membranes that allow vapor to pass through using aminoethers of boric acid (AEBA), modified with bulk adducts from diphenylol propane diglycidyl ether and ethanolamine (EM).
  • These modifications reduced the size of AEBA-EM particles and their viscosity, which helped the membranes become more permeable to vapor.
  • The enhanced vapor permeability, which was tripled in the modified polyurethanes, occurs due to reduced cluster size that creates channels for water molecules, improving the membranes' efficiency in dehydrating isopropanol.
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  • * Micronization via supercritical fluids can enhance drug properties, and adding just 2 mol% dimethyl sulfoxide significantly boosts mefenamic acid's solubility, making the drug more effective.
  • * Structural analysis using nuclear Overhauser effect spectroscopy revealed that the conformation of mefenamic acid varies depending on the solvent, underscoring the need to consider hidden conformers for optimizing drug micronization.
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  • The study focuses on the etherification reaction of -phosphoric acid (OPA) with polyoxypropylene glycol, using triethanolamine (TEOA) and triethylamine (TEA) as catalysts under low-temperature conditions.
  • It finds that triethylamine leads to complete etherification, resulting in branched OPA ethers and possible polyphosphate structures, while triethanolamine causes incomplete etherification, leaving some phosphate anions unreacted.
  • The research also includes an analysis of the kinetics of the reaction and the properties of polyurethane ionomer films created from aminoethers of -phosphoric acid (AEPA).
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  • Williams-Beuren syndrome (WBS) is caused by a deletion of genes on chromosome 7, leading to a variety of health issues due to protein malfunction.
  • The role of the protein methyltransferase WBSCR27 in WBS remains unclear, prompting researchers to create gene knockout mouse cell lines to identify its methylation targets.
  • Through structural analysis, they discovered that WBSCR27 has a characteristic Class I methyltransferase structure, and binding to S-adenosyl-L-homocysteine (SAH) helps form a substrate binding site, suggesting areas for future investigation.
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Transcriptional regulators select their targets from a large pool of similar genomic sites. The binding of the Drosophila dosage compensation complex (DCC) exclusively to the male X chromosome provides insight into binding site selectivity rules. Previous studies showed that the male-specific organizer of the complex, MSL2, and ubiquitous DNA-binding protein CLAMP directly interact and play an important role in the specificity of X chromosome binding.

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  • The study investigates how the pore inhibitor cyclosporin A (CsA) and its analogue alisporivir (Ali) impact rat skeletal muscle mitochondria, revealing that both increase calcium capacity without affecting oxidative phosphorylation at low concentrations.
  • At higher concentrations (5 μM), both agents suppress oxygen consumption, with Ali causing more notable effects, linked to reduced membrane potential and inhibited electron transport due to coenzyme Q mobility issues.
  • The research shows that neither CsA nor Ali impacts hydrogen peroxide production, but both decrease membrane fluidity in liposomes and mitochondrial membranes, suggesting their lipophilic properties may hinder mitochondrial efficiency.
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  • The paper discusses the design and analysis of a BODIPY biomarker combined with a thioterpene fragment to improve its structural and biological properties.
  • It examines how this conjugate interacts with erythrocytes (red blood cells) and its potential use in bioimaging, confirming the molecular structure through various spectroscopic methods.
  • The results indicate that the conjugate has high photostability and fluorescence, effectively entering erythrocytes without causing toxicity, which enhances its application in biological contexts.
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  • Azoximer bromide (AZB) was studied for its safety and efficacy in treating hospitalized COVID-19 patients, given its established benefits for upper respiratory infections in Russia.
  • In the study, 81 patients received AZB in combination with standard care, showing clinical improvement with no deaths reported during hospitalization, but one patient required ongoing respiratory support after 28 days.
  • Although AZB appeared to improve clinical outcomes and reduce hospitalization duration compared to a historical control group, more rigorous testing in a randomized, placebo-controlled trial is necessary to confirm its effectiveness.
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  • The article discusses the design and biological properties of a fluorescent compound called BODIPYmyrt, which is made from a specific monoterpenoid and a fluorophore.
  • BODIPYmyrt has a high quantum yield (close to 100%) in the 515-518 nm range, indicating its effectiveness in fluorescence applications.
  • It can penetrate bacterial and fungal cell membranes, making it useful for studying various types of bacteria and fungi, and also shows potential for targeting subcellular structures like mitochondria in mammalian cells.
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  • - This paper focuses on creating a fluorescent probe using meso-carboxysubstituted-BODIPY combined with a thioterpene fragment to examine the antiplatelet and anticoagulant effects of thioterpenoids.
  • - The researchers replaced a methoxy group in the BODIPY molecule with the thioterpene fragment to better understand the interactions of these compounds with membranes and receptors.
  • - The newly designed probe exhibits a high fluorescence quantum yield near 100% in the blue-green range (509-516 nm) and shows improved affinity to the platelet receptor P2Y through molecular docking studies.
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  • A study was conducted on 32 adults hospitalized with COVID-19, where they received the immune modulator azoximer bromide (AZB) alongside standard care, demonstrating a potential improvement in clinical status and a decrease in the severity of their condition.
  • Patients were treated with AZB for a total of approximately ten injections over their hospital stay, averaging 20 days, and all were alive at discharge with improved oxygen saturation and no major side effects reported.
  • While results indicated that AZB was safe and well tolerated, the study highlighted the need for further research through randomized, placebo-controlled trials to better determine its therapeutic effects in COVID-19 treatment.
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We present the design and parameters of a compact and mobile high-current pulse generator, which can be applied in the study of warm dense matter in university laboratories. The generator dimensions are 550 × 570 × 590 mm, the weight is ∼70 kg, and it consists of four "bricks" connected in parallel. Each brick, made up of 2 × 40 nF, 100 kV low-inductance capacitors connected in parallel, has its own multi-gap and multichannel ball gas spark switch, triggered via a capacitively coupled triggering by a positive polarity pulse of ∼80 kV amplitude and ∼15 ns rise time.

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Two-dimensional H-N HMBC NMR spectra of the well-known anticonvulsant carbamazepine dissolved in different organic solvents, recorded on an NMR spectrometer prove the existence of hidden conformers in saturated solutions. Obtained conformer distribution arises due to the presence of the solid phase in saturated solution. A weak influence of ring currents was revealed for different molecular conformations of carbamazepine dissolved in a saturated solution, which provides a simple approach to discovering hidden conformations.

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  • Telomerase is an enzyme that helps maintain genome integrity and allows continuous cell growth in eukaryotes, containing essential proteins like Est1 and Est3.
  • The study reveals the high-resolution structure of the Est3 protein from the thermotolerant yeast Hansenula polymorpha, demonstrating similarities with Est3 from other organisms like Saccharomyces cerevisiae and humans.
  • It emphasizes that both Est3 and Est1 are crucial for telomerase function, as their absence disrupts the formation of stable complexes and reduces the presence of another protein necessary for telomerase activity.
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  • Family I soluble inorganic pyrophosphatases (PPases) are crucial enzymes that hydrolyze inorganic pyrophosphate, facilitating various biosynthetic reactions.
  • The hexameric PPase from Mycobacterium tuberculosis (Mt-PPase) is a key target for developing new anti-tuberculosis drugs, but information on its structure in solution was previously lacking.
  • Advanced NMR techniques enabled researchers to assign resonance for over 95% of the residues in Mt-PPase and confirm that its solution structure aligns with its crystal structure, laying the groundwork for designing specific inhibitors for this enzyme.
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Cyclosporins B, C, D, and E were characterized by NMR spectroscopy, and backbone flexibility was studied by molecular dynamics simulation. Structures of the molecules were characterized by nuclear Overhauser effect spectroscopy, which revealed that the studied peptides have many common features. Molecular dynamics simulation showed that the backbone of cyclosporin E is relatively more rigid than in other peptides.

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  • Williams-Beuren syndrome results from a deletion in chromosome region 7q11.23, leading to the loss of 26 genes, including WBSCR27, whose function was previously unknown.
  • Research using NMR revealed the structure of murine WBSCR27 and categorized it as a Class I methyltransferase, showing that it binds S-(5'-adenosyl)-l-homocysteine (SAH) more tightly than its other cofactor, S-(5'-adenosyl)-l-methionine (SAM).
  • WBSCR27 also exhibits nucleosidase activity, cleaving adenine from SAH and related molecules, indicating that cofactor binding influences the enzyme's structure and
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