2024

Jump to: 2023, 2022

17 pages, 3586 KiB

Open AccessArticle

L-Asparaginase Conjugates from the Hyperthermophilic Archaea Thermococcus sibiricus with Improved Biocatalytic Properties

by Natalia V. Dobryakova, Maria V. Dumina, Alexander A. Zhgun, Marina V. Pokrovskaya, Svetlana S. Aleksandrova, Dmitry D. Zhdanov and Elena V. Kudryashova

Int. J. Mol. Sci. 2024, 25(8), 4174; https://doi.org/10.3390/ijms25084174 - 10 Apr 2024

Viewed by 332

Abstract

This study investigated the effect of polycationic and uncharged polymers (and oligomers) on the catalytic parameters and thermostability of L-asparaginase from Thermococcus sibiricus (TsA). This enzyme has potential applications in the food industry to decrease the formation of carcinogenic acrylamide during the processing [...] Read more.

This study investigated the effect of polycationic and uncharged polymers (and oligomers) on the catalytic parameters and thermostability of L-asparaginase from Thermococcus sibiricus (TsA). This enzyme has potential applications in the food industry to decrease the formation of carcinogenic acrylamide during the processing of carbohydrate-containing products. Conjugation with the polyamines polyethylenimine and spermine (PEI and Spm) or polyethylene glycol (PEG) did not significantly affect the secondary structure of the enzyme. PEG contributes to the stabilization of the dimeric form of TsA, as shown by HPLC. Furthermore, neither polyamines nor PEG significantly affected the binding of the L-Asn substrate to TsA. The conjugates showed greater maximum activity at pH 7.5 and 85 °C, 10–50% more than for native TsA. The pH optima for both TsA-PEI and TsA-Spm conjugates were shifted to lower pH ranges from pH 10 (for the native enzyme) to pH 8.0. Additionally, the TsA-Spm conjugate exhibited the highest activity at pH 6.5–9.0 among all the samples. Furthermore, the temperature optimum for activity at pH 7.5 shifted from 90–95 °C to 80–85 °C for the conjugates. The thermal inactivation mechanism of TsA-PEG appeared to change, and no aggregation was observed in contrast to that of the native enzyme. This was visually confirmed and supported by the analysis of the CD spectra, which remained almost unchanged after heating the conjugate solution. These results suggest that TsA-PEG may be a more stable form of TsA, making it a potentially more suitable option for industrial use. Full article

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2023

Jump to: 2024, 2022

24 pages, 10446 KiB

Open AccessArticle

Macromolecular Design and Engineering of New Amphiphilic N-Vinylpyrrolidone Terpolymers for Biomedical Applications

by Svetlana V. Kurmaz, Evgenia O. Perepelitsina, Sergey G. Vasiliev, Irina A. Avilova, Igor I. Khodos, Vladimir A. Kurmaz, Dmitry A. Chernyaev, Yuliya V. Soldatova, Natalia V. Filatova and Irina I. Faingold

Int. J. Mol. Sci. 2023, 24(20), 15170; https://doi.org/10.3390/ijms242015170 - 14 Oct 2023

Viewed by 757

Abstract

New amphiphilic VP-(di)methacrylate terpolymers of different monomer compositions and topologies have been synthesized by radical polymerization in toluene without any growth regulator of polymer chains. Their structures and properties in solid state and water solution were studied by double-detector size-exclusion chromatography; IR-, ¹ [...] Read more.

New amphiphilic VP-(di)methacrylate terpolymers of different monomer compositions and topologies have been synthesized by radical polymerization in toluene without any growth regulator of polymer chains. Their structures and properties in solid state and water solution were studied by double-detector size-exclusion chromatography; IR-, ¹H, and ¹³C NMR-spectroscopy; DLS, TEM, TG, and DSC methods. The composition of the VP-AlkMA-TEGDM monomer mixture has been established to regulate the topology of the resulting macromolecules. The studied terpolymers presented on TEM images as individual low-contrast particles and their conglomerates of various sizes with highly ordered regions; in general, they are amorphous structures. None of the terpolymers demonstrated cytotoxic effects for noncancerous Vero and tumor HeLa cells. Hydrophobic D-α-tocopherol (TP) was encapsulated in terpolymer nanoparticles (NPs), and its antioxidant activity was evaluated by ABTS (radical monocation 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)) or DPPH (2,2′-diphenyl-1-picrylhydrazyl) methods. The reaction efficiency depends on the TP-NP type. The IC₅₀ values for the decolorization reaction of ABTS^•+ and DPPH inhibition in the presence of initial and encapsulated TP were obtained. Full article

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23 pages, 1177 KiB

Open AccessReview

Recent Advances in Miscanthus Macromolecule Conversion: A Brief Overview

by Galina F. Mironova, Vera V. Budaeva, Ekaterina A. Skiba, Yulia A. Gismatulina, Ekaterina I. Kashcheyeva and Gennady V. Sakovich

Int. J. Mol. Sci. 2023, 24(16), 13001; https://doi.org/10.3390/ijms241613001 - 20 Aug 2023

Cited by 1 | Viewed by 1523

Abstract

Miscanthus is a valuable renewable feedstock and has a significant potential for the manufacture of diverse biotechnology products based on macromolecules such as cellulose, hemicelluloses and lignin. Herein, we overviewed the state-of-the art of research on the conversion of miscanthus polymers into biotechnology [...] Read more.

Miscanthus is a valuable renewable feedstock and has a significant potential for the manufacture of diverse biotechnology products based on macromolecules such as cellulose, hemicelluloses and lignin. Herein, we overviewed the state-of-the art of research on the conversion of miscanthus polymers into biotechnology products comprising low-molecular compounds and macromolecules: bioethanol, biogas, bacterial cellulose, enzymes (cellulases, laccases), lactic acid, lipids, fumaric acid and polyhydroxyalkanoates. The present review aims to assess the potential of converting miscanthus polymers in order to develop sustainable technologies. Full article

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16 pages, 16968 KiB

Open AccessArticle

A Genomic Analysis of the Bacillus Bacteriophage Kirovirus kirovense Kirov and Its Ability to Preserve Milk

by Olesya A. Kazantseva, Anna V. Skorynina, Emma G. Piligrimova, Natalya A. Ryabova and Andrey M. Shadrin

Int. J. Mol. Sci. 2023, 24(16), 12584; https://doi.org/10.3390/ijms241612584 - 09 Aug 2023

Viewed by 1096

Abstract

Bacteriophages are widely recognized as alternatives to traditional antibiotics commonly used in the treatment of bacterial infection diseases and in the food industry, as phages offer a potential solution in combating multidrug-resistant bacterial pathogens. In this study, we describe a novel bacteriophage, Kirovirus [...] Read more.

Bacteriophages are widely recognized as alternatives to traditional antibiotics commonly used in the treatment of bacterial infection diseases and in the food industry, as phages offer a potential solution in combating multidrug-resistant bacterial pathogens. In this study, we describe a novel bacteriophage, Kirovirus kirovense Kirov, which infects members of the Bacillus cereus group. Kirovirus kirovense Kirov is a broad-host-range phage belonging to the Caudoviricetes class. Its chromosome is a linear 165,667 bp double-stranded DNA molecule that contains two short, direct terminal repeats, each 284 bp long. According to bioinformatics predictions, the genomic DNA contains 275 protein-coding genes and 5 tRNA genes. A comparative genomic analysis suggests that Kirovirus kirovense Kirov is a novel species within the Kirovirus genus, belonging to the Andregratiavirinae subfamily. Kirovirus kirovense Kirov demonstrates the ability to preserve and decontaminate B. cereus from cow milk when present in milk at a concentration of 10⁴ PFU/mL. After 4 h of incubation with the phage, the bacterial titer drops from 10⁵ to less than 10² CFU/mL. Full article

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13 pages, 3778 KiB

Open AccessArticle

Composites of N-butyl-N-methyl-1-phenylpyrrolo[1,2-a]pyrazine-3-carboxamide with Polymers: Effect of Crystallinity on Solubility and Stability

by Vladimir B. Markeev, Evgenia V. Blynskaya, Sergey V. Tishkov, Konstantin V. Alekseev, Anna I. Marakhova, Alexandre A. Vetcher and Alexander Y. Shishonin

Int. J. Mol. Sci. 2023, 24(15), 12215; https://doi.org/10.3390/ijms241512215 - 30 Jul 2023

Cited by 2 | Viewed by 1028

Abstract

This work aimed to develop and characterize a water-soluble, high-release active pharmaceutical ingredient (API) composite based on the practically water-insoluble API N-butyl-N-methyl-1-phenylpyrrolo[1,2-a]pyrazine-3-carboxamide (GML-3), a substance with antidepressant and anxiolytic action. This allows to ensure the bioavailability of the medicinal product of combined action. [...] Read more.

This work aimed to develop and characterize a water-soluble, high-release active pharmaceutical ingredient (API) composite based on the practically water-insoluble API N-butyl-N-methyl-1-phenylpyrrolo[1,2-a]pyrazine-3-carboxamide (GML-3), a substance with antidepressant and anxiolytic action. This allows to ensure the bioavailability of the medicinal product of combined action. Composites obtained by the method of creating amorphous solid dispersions, where polyvinylpyrrolidone (PVP) or Soluplus^® was used as a polymer, were studied for crystallinity, stability and the release of API from the composite into purified water. The resulting differential scanning calorimetry (DSC), powder X-ray diffractometry (PXRD), and dissolution test data indicate that the resulting composites are amorphous at 1:15 API: polymer ratios for PVP and 1:5 for Soluplus^®, which ensures the solubility of GML-3 in purified water and maintaining the supercritical state in solution. Full article

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10 pages, 11645 KiB

Open AccessArticle

Peculiar Properties of Template-Assisted Aniline Polymerization in a Buffer Solution Using Laccase and a Laccase–Mediator System as Compared with Chemical Polymerization

by Olga Morozova, Irina Vasil’eva, Galina Shumakovich, Elena Zaitseva and Alexander Yaropolov

Int. J. Mol. Sci. 2023, 24(14), 11374; https://doi.org/10.3390/ijms241411374 - 12 Jul 2023

Viewed by 796

Abstract

The conventional chemical polymerization of aniline has been described in multiple publications, while enzymatic polymerization has been poorly explored. A comparative study of the template-assisted enzymatic and chemical polymerization of aniline in a buffer solution of sodium dodecylbenzenesulfonate micelles was performed for the [...] Read more.

The conventional chemical polymerization of aniline has been described in multiple publications, while enzymatic polymerization has been poorly explored. A comparative study of the template-assisted enzymatic and chemical polymerization of aniline in a buffer solution of sodium dodecylbenzenesulfonate micelles was performed for the first time. The high-redox potential laccase from the fungus Trametes hirsuta was used as a catalyst and air oxygen served as an oxidant. Potentiometric and spectral methods have shown that oligomeric/polymeric products of the enzymatic polymerization of aniline are synthesized in the conducting emeraldine salt form immediately after the reaction is initiated by the enzyme. The use of the laccase–mediator system enabled a higher rate of enzymatic polymerization and a higher yield of final products. Potassium octocyanomolybdate (IV) served as a redox mediator. The products of the enzymatic polymerization of aniline were studied by the ATR-FTIR, MALDI-TOF and atomic force microscopy methods. The chemical oxidative polymerization of aniline under the same conditions resulted in forming a non-conducting dark brown product. Full article

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16 pages, 5146 KiB

Open AccessArticle

Complexation of Bromelain, Ficin, and Papain with the Graft Copolymer of Carboxymethyl Cellulose Sodium Salt and N-Vinylimidazole Enhances Enzyme Proteolytic Activity

by Andrey V. Sorokin, Svetlana S. Goncharova, Maria S. Lavlinskaya, Marina G. Holyavka, Dzhigangir A. Faizullin, Yuriy F. Zuev, Maxim S. Kondratyev and Valeriy G. Artyukhov

Int. J. Mol. Sci. 2023, 24(14), 11246; https://doi.org/10.3390/ijms241411246 - 08 Jul 2023

Cited by 2 | Viewed by 934

Abstract

This study investigates the features of interactions between cysteine proteases (bromelain, ficin, and papain) and a graft copolymer of carboxymethyl cellulose sodium salt with N-vinylimidazole. The objective is to understand the influence of this interactions on the proteolytic activity and stability of [...] Read more.

This study investigates the features of interactions between cysteine proteases (bromelain, ficin, and papain) and a graft copolymer of carboxymethyl cellulose sodium salt with N-vinylimidazole. The objective is to understand the influence of this interactions on the proteolytic activity and stability of the enzymes. The enzymes were immobilized through complexation with the carrier. The interaction mechanism was examined using Fourier-transform infrared spectroscopy and flexible molecular docking simulations. The findings reveal that the enzymes interact with the functional groups of the carrier via amino acid residues, resulting in the formation of secondary structure elements and enzyme’s active sites. These interactions induce modulation of active site of the enzymes, leading to an enhancement in their proteolytic activity. Furthermore, the immobilized enzymes demonstrate superior stability compared to their native counterparts. Notably, during a 21-day incubation period, no protein release from the conjugates was observed. These results suggest that the complexation of the enzymes with the graft copolymer has the potential to improve their performance as biocatalysts, with applications in various fields such as biomedicine, pharmaceutics, and biotechnology. Full article

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21 pages, 2937 KiB

Open AccessArticle

Dispersant and Protective Roles of Amphiphilic Poly(ethylene phosphate) Block Copolymers in Polyester/Bone Mineral Composites

by Ilya Nifant’ev, Alexander Tavtorkin, Pavel Komarov, Egor Kretov, Sofia Korchagina, Maria Chinova, Dmitry Gavrilov and Pavel Ivchenko

Int. J. Mol. Sci. 2023, 24(13), 11175; https://doi.org/10.3390/ijms241311175 - 06 Jul 2023

Cited by 1 | Viewed by 1053

Abstract

Composites of synthetic bone mineral substitutes (BMS) and biodegradable polyesters are of particular interest for bone surgery and orthopedics. Manufacturing of composite scaffolds commonly uses mixing of the BMS with polymer melts. Melt processing requires a high homogeneity of the mixing, and is [...] Read more.

Composites of synthetic bone mineral substitutes (BMS) and biodegradable polyesters are of particular interest for bone surgery and orthopedics. Manufacturing of composite scaffolds commonly uses mixing of the BMS with polymer melts. Melt processing requires a high homogeneity of the mixing, and is complicated by BMS-promoted thermal degradation of polymers. In our work, poly(L-lactide) (PLLA) and poly(ε-caprolactone) (PCL) composites reinforced by commercial β-tricalcium phosphate (βTCP) or synthesized carbonated hydroxyapatite with hexagonal and plate-like crystallite shapes (hCAp and pCAp, respectively) were fabricated using injection molding. pCAp-based composites showed advanced mechanical and thermal characteristics, and the best set of mechanical characteristics was observed for the PLLA-based composite containing 25 wt% of pCAp. To achieve compatibility of polyesters and pCAp, reactive block copolymers of PLLA or PCL with poly(tert-butyl ethylene phosphate) (C1 and C2, respectively) were introduced to the composite. The formation of a polyester-b-poly(ethylene phosphoric acid) (PEPA) compatibilizer during composite preparation, followed by chemical binding of PEPA with pCAp, have been proved experimentally. The presence of 5 wt% of the compatibilizer provided deeper homogenization of the composite, resulting in a marked increase in strength and moduli as well as a more pronounced nucleation effect during isothermal crystallization. The use of C1 increased the thermal stability of the PLLA-based composite, containing 25 wt% of pCAp. In view of positive impacts of polyester-b-PEPA on composite homogeneity, mechanical characteristics, and thermal stability, polyester-b-PEPA will find application in the further development of composite materials for bone surgery and orthopedics. Full article

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16 pages, 15708 KiB

Open AccessArticle

Morphological Diversity of Dps Complex with Genomic DNA

by Yuri Chesnokov, Roman Kamyshinsky, Andrey Mozhaev, Eleonora Shtykova, Alexander Vasiliev, Ivan Orlov and Liubov Dadinova

Int. J. Mol. Sci. 2023, 24(10), 8534; https://doi.org/10.3390/ijms24108534 - 10 May 2023

Cited by 2 | Viewed by 1504

Abstract

In response to adverse environmental factors, Escherichia coli cells actively produce Dps proteins which form ordered complexes (biocrystals) with bacterial DNA to protect the genome. The effect of biocrystallization has been described extensively in the scientific literature; furthermore, to date, the structure of [...] Read more.

In response to adverse environmental factors, Escherichia coli cells actively produce Dps proteins which form ordered complexes (biocrystals) with bacterial DNA to protect the genome. The effect of biocrystallization has been described extensively in the scientific literature; furthermore, to date, the structure of the Dps–DNA complex has been established in detail in vitro using plasmid DNA. In the present work, for the first time, Dps complexes with E. coli genomic DNA were studied in vitro using cryo-electron tomography. We demonstrate that genomic DNA forms one-dimensional crystals or filament-like assemblies which transform into weakly ordered complexes with triclinic unit cells, similar to what is observed for plasmid DNA. Changing such environmental factors as pH and KCl and MgCl₂ concentrations leads to the formation of cylindrical structures. Full article

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12 pages, 2362 KiB

Open AccessArticle

Determination of Phenol with Peroxidase Immobilized on CaCO₃

by Aleksandr L. Kim, Alexey V. Dubrovskii, Egor V. Musin and Sergey A. Tikhonenko

Int. J. Mol. Sci. 2023, 24(7), 6766; https://doi.org/10.3390/ijms24076766 - 05 Apr 2023

Viewed by 1389

Abstract

Phenols are widely used in industries despite their toxicity, which requires governments to limit their concentration in water to 5 mg/L before discharge to the city sewer. Thus, it is essential to develop a rapid, simple, and low-cost detection method for phenol. This [...] Read more.

Phenols are widely used in industries despite their toxicity, which requires governments to limit their concentration in water to 5 mg/L before discharge to the city sewer. Thus, it is essential to develop a rapid, simple, and low-cost detection method for phenol. This study explored two pathways of peroxidase immobilization to develop a phenol detection system: peroxidase encapsulation into polyelectrolyte microcapsules and peroxidase captured by CaCO₃. The encapsulation of peroxidase decreased enzyme activity by 96%; thus, this method cannot be used for detection systems. The capturing process of peroxidase by CaCO₃ microspherulites did not affect the maximum reaction rate and the Michaelis constant of peroxidase. The native peroxidase—Vmax = 109 µM/min, Km = 994 µM; CaCO₃–peroxidase—Vmax = 93.5 µM/min, Km = 956 µM. Ultimately, a reusable phenol detection system based on CaCO₃ microparticles with immobilized peroxidase was developed, capable of detecting phenol in the range of 700 ng/mL to 14 µg/mL, with an error not exceeding 5%, and having a relatively low cost and production time. The efficiency of the system was confirmed by determining the content of phenol in a paintwork product. Full article

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14 pages, 9455 KiB

Open AccessArticle

Polyelectrolyte Microcapsules—A Promising Target Delivery System of Amiodarone with the Possibility of Prolonged Release

by Aleksandr L. Kim, Egor V. Musin, Munojat J. Oripova, Yulia I. Oshchepkova, Shavkat I. Salikhov and Sergey A. Tikhonenko

Int. J. Mol. Sci. 2023, 24(4), 3348; https://doi.org/10.3390/ijms24043348 - 08 Feb 2023

Cited by 2 | Viewed by 1573

Abstract

Atrial fibrillation is one of the most common cardiac arrhythmias. Pharmacological preparations are used for treatment to control heart rate and rhythm. Amiodarone is one of these highly effective preparations, but, at the same time, it has significant toxicity and nonspecific accumulation in [...] Read more.

Atrial fibrillation is one of the most common cardiac arrhythmias. Pharmacological preparations are used for treatment to control heart rate and rhythm. Amiodarone is one of these highly effective preparations, but, at the same time, it has significant toxicity and nonspecific accumulation in tissues. The drug delivery system based on polyelectrolyte microcapsules is one of the solutions. For this purpose, we compared different encapsulation methods of amiodaron: monoammonium salt of glycyrrhizic acid (Am:MASGA) complex (molar ratio 1:8). The concentration of amiodarone was determined by spectrophotometric methods at 251 nm. It has been shown that the co-precipitation method allows capturing 8% of Am:MASGA by CaCO₃ microspherulites, which is not sufficient for the long-acting drug. The adsorption method allows encapsulating more than 30% of Am:MASGA into CaCO₃ microspherulites and polyelectrolyte microcapsules CaCO₃(PAH/PSS)₃, but, at the same time, an insignificant amount of substance is released into the incubation medium. The development of delivery and long-acting drug system based on such methods are not inexpedient. The most appropriate encapsulation method of Am:MASGA is the adsorption method into polyelectrolyte microcapsules with complex interpolyelectrolyte structure (PAH/PSS)₃. Such a type of PMC adsorbed about 50% of the initial amount of the substance and 25–30% of Am:MASGA was released into the medium after 115 h of incubation. The adsorption of Am:MASGA by polyelectrolyte microcapsules has electrostatic nature as evidenced by the acceleration of the release by 1.8 times as ionic strength increases Full article

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11 pages, 2801 KiB

Open AccessArticle

Sorption of Salts of Various Metals by Polyelectrolyte Microcapsules

by Aleksandr L. Kim, Alexey V. Dubrovskii, Egor V. Musin and Sergey A. Tikhonenko

Int. J. Mol. Sci. 2023, 24(3), 2834; https://doi.org/10.3390/ijms24032834 - 01 Feb 2023

Cited by 1 | Viewed by 1383

Abstract

Anthropogenic activity negatively affects the environment by polluting it with the salts of various metals. One of the ways to reduce this influence is to use water purification methods for the salts of various metals. Water purification methods based on nanomaterials are promising. [...] Read more.

Anthropogenic activity negatively affects the environment by polluting it with the salts of various metals. One of the ways to reduce this influence is to use water purification methods for the salts of various metals. Water purification methods based on nanomaterials are promising. In this regard, we proposed to study polyelectrolyte microcapsules (PMC) as a promising sorption agent for the salts of various metals. It was found that the polystyrene sulfonate-polyallylamine (PSS-PAH) polyelectrolyte complex and polyelectrolyte microcapsules of different compositions are not able to adsorb salts CuSO₄, Pb(NO)₃, FeCl₃, and CuCl₂. At the same time, it was found that all types of capsules, except for (PSS/PAH)₂/PSS, are capable of sorbing about 420 µg of K₃[Fe(CN)₆] and about 500 µg of K₄[Fe(CN)₆] from solution. The adsorption of polyelectrolyte microcapsules has an electrostatic nature which is confirmed by increases in the sorption capacity of PMC of K₃[Fe(CN)₆] and K₄[Fe(CN)₆] with decreases in the pH of the solution. Also, It was confirmed that the sorption process of PMC of K₃[Fe(CN)₆] and K₄[Fe(CN)₆] is concentration dependent and has the limitation of the number of binding sites. Full article

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12 pages, 939 KiB

Open AccessReview

Analysis of Single Biomacromolecules and Viruses: Is It a Myth or Reality?

by Tatyana O. Pleshakova, Yuri D. Ivanov, Anastasia A. Valueva, Victoria V. Shumyantseva, Ekaterina V. Ilgisonis, Elena A. Ponomarenko, Andrey V. Lisitsa, Vladimir P. Chekhonin and Alexander I. Archakov

Int. J. Mol. Sci. 2023, 24(3), 1877; https://doi.org/10.3390/ijms24031877 - 18 Jan 2023

Cited by 1 | Viewed by 1591

Abstract

The beginning of the twenty-first century witnessed novel breakthrough research directions in the life sciences, such as genomics, transcriptomics, translatomics, proteomics, metabolomics, and bioinformatics. A newly developed single-molecule approach addresses the physical and chemical properties and the functional activity of single (individual) biomacromolecules [...] Read more.

The beginning of the twenty-first century witnessed novel breakthrough research directions in the life sciences, such as genomics, transcriptomics, translatomics, proteomics, metabolomics, and bioinformatics. A newly developed single-molecule approach addresses the physical and chemical properties and the functional activity of single (individual) biomacromolecules and viral particles. Within the alternative approach, the combination of “single-molecule approaches” is opposed to “omics approaches”. This new approach is fundamentally unique in terms of its research object (a single biomacromolecule). Most studies are currently performed using postgenomic technologies that allow the properties of several hundreds of millions or even billions of biomacromolecules to be analyzed. This paper discusses the relevance and theoretical, methodological, and practical issues related to the development potential of a single-molecule approach using methods based on molecular detectors. Full article

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52 pages, 25594 KiB

Open AccessReview

Design, Synthesis and Actual Applications of the Polymers Containing Acidic P–OH Fragments: Part 2—Sidechain Phosphorus-Containing Polyacids

by Ilya E. Nifant’ev and Pavel V. Ivchenko

Int. J. Mol. Sci. 2023, 24(2), 1613; https://doi.org/10.3390/ijms24021613 - 13 Jan 2023

Cited by 3 | Viewed by 2085

Abstract

Macromolecules containing acidic fragments in side-groups—polyacids—occupy a special place among synthetic polymers. Properties and applications of polyacids are directly related to the chemical structure of macromolecules: the nature of the acidic groups, polymer backbone, and spacers between the main chain and acidic groups. [...] Read more.

Macromolecules containing acidic fragments in side-groups—polyacids—occupy a special place among synthetic polymers. Properties and applications of polyacids are directly related to the chemical structure of macromolecules: the nature of the acidic groups, polymer backbone, and spacers between the main chain and acidic groups. The chemical nature of the phosphorus results in the diversity of acidic >P(O)OH fragments in sidechain phosphorus-containing polyacids (PCPAs) that can be derivatives of phosphoric or phosphinic acids. Sidechain PCPAs have many similarities with other polyacids. However, due to the relatively high acidity of –P(O)(OH)₂ fragment, bone and mineral affinity, and biocompatibility, sidechain PCPAs have immense potential for diverse applications. Synthetic approaches to sidechain PCPAs also have their own specifics. All these issues are discussed in the present review. Full article

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2022

Jump to: 2024, 2023

12 pages, 2443 KiB

Open AccessArticle

Structural and Functional Characterization of β−lytic Protease from Lysobacter capsici VKM B−2533^T

by Alexey Afoshin, Svetlana Tishchenko, Azat Gabdulkhakov, Irina Kudryakova, Inna Galemina, Dmitry Zelenov, Elena Leontyevskaya, Sofia Saharova and Natalya Leontyevskaya (Vasilyeva)

Int. J. Mol. Sci. 2022, 23(24), 16100; https://doi.org/10.3390/ijms232416100 - 17 Dec 2022

Cited by 2 | Viewed by 1223

Abstract

The crystal structure of the Lysobacter capsici VKM B−2533^T β-lytic protease (Blp), a medicinally promising antimicrobial enzyme, was first solved. Blp was established to possess a folding characteristic of the M23 protease family. The groove of the Blp active site, as compared [...] Read more.

The crystal structure of the Lysobacter capsici VKM B−2533^T β-lytic protease (Blp), a medicinally promising antimicrobial enzyme, was first solved. Blp was established to possess a folding characteristic of the M23 protease family. The groove of the Blp active site, as compared with that of the LasA structural homologue from Pseudomonas aeruginosa, was found to have amino acid differences. Biochemical analysis revealed no differences in the optimal reaction conditions for manifesting Blp and LasA bacteriolytic activities. At the same time, Blp had a broader range of action against living and autoclaved target cells. The results suggest that the distinction in the geometry of the active site and the charge of amino acid residues that form the active site groove can be important for the hydrolysis of different peptidoglycan types in target cells. Full article

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14 pages, 831 KiB

Open AccessArticle

Semiclassical Theory of Multistage Nonequilibrium Electron Transfer in Macromolecular Compounds in Polar Media with Several Relaxation Timescales

by Serguei V. Feskov

Int. J. Mol. Sci. 2022, 23(24), 15793; https://doi.org/10.3390/ijms232415793 - 13 Dec 2022

Cited by 1 | Viewed by 905

Abstract

Many specific features of ultrafast electron transfer (ET) reactions in macromolecular compounds can be attributed to nonequilibrium configurations of intramolecular vibrational degrees of freedom and the environment. In photoinduced ET, nonequilibrium nuclear configurations are often produced at the stage of optical excitation, but [...] Read more.

Many specific features of ultrafast electron transfer (ET) reactions in macromolecular compounds can be attributed to nonequilibrium configurations of intramolecular vibrational degrees of freedom and the environment. In photoinduced ET, nonequilibrium nuclear configurations are often produced at the stage of optical excitation, but they can also be the result of electron tunneling itself, i.e., fast redistribution of charges within the macromolecule. A consistent theoretical description of ultrafast ET requires an explicit consideration of the nuclear subsystem, including its evolution between electron jumps. In this paper, the effect of the multi-timescale nuclear reorganization on ET transitions in macromolecular compounds is studied, and a general theory of ultrafast ET in non-Debye polar environments with a multi-component relaxation function is developed. Particular attention is paid to designing the multidimensional space of nonequilibrium nuclear configurations, as well as constructing the diabatic free energy surfaces for the ET states. The reorganization energies of individual ET transitions, the equilibrium energies of ET states, and the relaxation properties of the environment are used as input data for the theory. The effect of the system-environment interaction on the ET kinetics is discussed, and mechanisms for enhancing the efficiency of charge separation in macromolecular compounds are analyzed. Full article

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9 pages, 1273 KiB

Open AccessArticle

Gallium (III) Complexes Based on Aminobisphenolate Ligands: Extremely High Active ROP-Initiators from Well-Known and Easily Accessible Compounds

by Badma N. Mankaev, Leyla F. Hasanova, Andrei V. Churakov, Mikhail P. Egorov and Sergey S. Karlov

Int. J. Mol. Sci. 2022, 23(24), 15649; https://doi.org/10.3390/ijms232415649 - 09 Dec 2022

Cited by 4 | Viewed by 1328

Abstract

We report herein the synthesis and full characterizations of the first examples of gallium complexes based on “privileged” aminobisphenolate ligands which are easily available. These complexes turned out to be extremely active in the ring-opening polymerization of ε-caprolactone even at room temperature and [...] Read more.

We report herein the synthesis and full characterizations of the first examples of gallium complexes based on “privileged” aminobisphenolate ligands which are easily available. These complexes turned out to be extremely active in the ring-opening polymerization of ε-caprolactone even at room temperature and highly active in the ROP of L-lactide. The combination of factors such as the easy availability of these compounds and the supposedly low toxicity, together with the extremely high activity in ROP, allows us to consider these compounds as suitable for use on an industrial scale for the synthesis of biodegradable polymers for biomedical applications. Full article

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11 pages, 2492 KiB

Open AccessArticle

The Novel Gallium Aminobisphenolate Initiator of the Ring-Opening Copolymerization of L-Lactide and ε-Caprolactone: A Computational Study

by Maxim V. Zabalov, Badma N. Mankaev, Mikhail P. Egorov and Sergey S. Karlov

Int. J. Mol. Sci. 2022, 23(24), 15523; https://doi.org/10.3390/ijms232415523 - 08 Dec 2022

Cited by 4 | Viewed by 1179

Abstract

Density functional theory (DFT) simulations of ring-opening copolymerization of ε-caprolactone (CL) and L-lactide (LA) in presence of novel gallium complex on aminobis (phenolate) ligand are conducted. The initial steps of polymerization of CL and LA as well as the first steps of propagation [...] Read more.

Density functional theory (DFT) simulations of ring-opening copolymerization of ε-caprolactone (CL) and L-lactide (LA) in presence of novel gallium complex on aminobis (phenolate) ligand are conducted. The initial steps of polymerization of CL and LA as well as the first steps of propagation which led to LGa-LA-LA-OMe, LGa-LA-CL-OMe, LGa-CL-LA-OMe, or LGa-CL-CL-OMe derivatives have been analyzed in detail. According to these data, the studied catalyst is a rare example of a catalyst in which, during copolymerization, the polymerization of CL should proceed faster than LA. Thus, we predict the formation of a mainly block copolymer poly(CL-block-LA) using this catalyst. Full article

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14 pages, 2665 KiB

Open AccessArticle

The Essential Role of Prolines and Their Conformation in Allosteric Regulation of Kaiso Zinc Finger DNA-Binding Activity by the Adjacent C-Terminal Loop

by Elena Belova, Oksana Maksimenko, Pavel Georgiev and Artem Bonchuk

Int. J. Mol. Sci. 2022, 23(24), 15494; https://doi.org/10.3390/ijms232415494 - 07 Dec 2022

Viewed by 1296

Abstract

Kaiso is a methyl-DNA-binding protein containing three C2H2 zinc fingers with a C-terminal extension that participates in DNA binding. The linker between the last zinc finger and the DNA-binding portion of the extension contains two prolines that are highly conserved in vertebrates and [...] Read more.

Kaiso is a methyl-DNA-binding protein containing three C2H2 zinc fingers with a C-terminal extension that participates in DNA binding. The linker between the last zinc finger and the DNA-binding portion of the extension contains two prolines that are highly conserved in vertebrates and in cognate ZBTB4 and ZBTB38 proteins. Prolines provide chain rigidity and can exist in cis and trans conformations that can be switched by proline isomerases, affecting protein function. We found that substitution of the conserved proline P588, but not of P577, to alanine, negatively affected KaisoDNA-binding according to molecular dynamics simulation and in vitro DNA-binding assays. Molecular dynamics simulations of the Kaiso DNA-binding domain with P588 either substituted to alanine or switched to the cis-conformation revealed similar alterations in the H-bonding network and uncovered allosteric effects leading to structural rearrangements in the entire domain that resulted in the weakening of DNA-binding affinity. The substitution of proline with a large hydrophobic residue led to the same negative effects despite its ability to partially rescue the intrinsic DNA-binding activity of the C-terminal loop. Thus, the presence of the C-terminal extension and cis-conformation of proline residues are essential for efficient Kaiso–DNA binding, which likely involves intramolecular tension squeezing the DNA chain. Full article

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36 pages, 10645 KiB

Open AccessReview

Agricultural Applications of Superabsorbent Polymer Hydrogels

by Elena L. Krasnopeeva, Gaiane G. Panova and Alexander V. Yakimansky

Int. J. Mol. Sci. 2022, 23(23), 15134; https://doi.org/10.3390/ijms232315134 - 01 Dec 2022

Cited by 20 | Viewed by 5550

Abstract

This review presents data from the past five years on the use of polymeric superabsorbent hydrogels in agriculture as water and nutrient storage and retention materials, as well as additives that improve soil properties. The use of synthetic and natural polymeric hydrogels for [...] Read more.

This review presents data from the past five years on the use of polymeric superabsorbent hydrogels in agriculture as water and nutrient storage and retention materials, as well as additives that improve soil properties. The use of synthetic and natural polymeric hydrogels for these purposes is considered. Although natural polymers, such as various polysaccharides, have undoubted advantages related to their biocompatibility, biodegradability, and low cost, they are inferior to synthetic polymers in terms of water absorption and water retention properties. In this regard, the most promising are semi-synthetic polymeric superabsorbents based on natural polymers modified with additives or grafted chains of synthetic polymers, which can combine the advantages of natural and synthetic polymeric hydrogels without their disadvantages. Such semi-synthetic polymers are of great interest for agricultural applications, especially in dry regions, also because they can be used to create systems for the slow release of nutrients into the soil, which are necessary to increase crop yields using environmentally friendly technologies. Full article

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41 pages, 14481 KiB

Open AccessReview

Design, Synthesis and Actual Applications of the Polymers Containing Acidic P–OH Fragments: Part 1. Polyphosphodiesters

by Ilya E. Nifant’ev and Pavel V. Ivchenko

Int. J. Mol. Sci. 2022, 23(23), 14857; https://doi.org/10.3390/ijms232314857 - 28 Nov 2022

Cited by 3 | Viewed by 2168

Abstract

Among natural and synthetic polymers, main-chain phosphorus-containing polyacids (PCPAs) (polyphosphodiesters), stand in a unique position at the intersection of chemistry, physics, biology and medicine. The structural similarity of polyphosphodiesters PCPAs to natural nucleic and teichoic acids, their biocompatibility, mimicking to biomolecules providing the [...] Read more.

Among natural and synthetic polymers, main-chain phosphorus-containing polyacids (PCPAs) (polyphosphodiesters), stand in a unique position at the intersection of chemistry, physics, biology and medicine. The structural similarity of polyphosphodiesters PCPAs to natural nucleic and teichoic acids, their biocompatibility, mimicking to biomolecules providing the ‘stealth effect’, high bone mineral affinity of polyphosphodiesters resulting in biomineralization at physiological conditions, and adjustable hydrolytic stability of polyphosphodiesters are the basis for various biomedical, industrial and household applications of this type of polymers. In the present review, we discuss the synthesis, properties and actual applications of polyphosphodiesters. Full article

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13 pages, 2377 KiB

Open AccessArticle

Unusual Effect of α-olefins as Chain Transfer Agents in Ethylene Polymerization over the Catalyst with Nonsymmetrical Bis(imino)pyridine Complex of Fe(II) and Modified Methylalumoxane (MMAO) Cocatalyst

by Nina V. Semikolenova, Mikhail A. Matsko, Vladimir A. Zakharov and Wen-Hua Sun

Int. J. Mol. Sci. 2022, 23(22), 14384; https://doi.org/10.3390/ijms232214384 - 19 Nov 2022

Viewed by 1031

Abstract

Ethylene polymerization with bis(imino)pyridlyiron precatalysts generally produces linear polyethylene (PE) even with the presence of α-olefins because α-olefins are not incorporated into polymeric products. Interestingly, α-olefins, such as hexene-1 or butene-1, have been found to act as effective chain transfer agents in the [...] Read more.

Ethylene polymerization with bis(imino)pyridlyiron precatalysts generally produces linear polyethylene (PE) even with the presence of α-olefins because α-olefins are not incorporated into polymeric products. Interestingly, α-olefins, such as hexene-1 or butene-1, have been found to act as effective chain transfer agents in the ethylene polymerization promoted by nonsymmetrical bis(imino)pyridyliron complexes with modified methylalumoxane (MMAO), resulting in higher catalytic activities with higher amounts of polymers with lower molecular weights, and, more importantly, narrower molecular weight distributions of the resultant polyethylenes (PE). This phenomenon confirms the assistance of α-olefins in the chain-termination reaction of iron-initiated polymerization and regeneration of the active species for further polymerization. Besides higher activities of the catalytic system, the formation of linear PE with trans-vinylene terminal groups and lower molecular weights are explained. The observation will provide a new pathway for enhancing catalytic activity and improving the quality of polyethylenes obtained by regulation of molecular weights and molecular weight distribution. Full article

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13 pages, 1800 KiB

Open AccessArticle

Microarray Profiling of Vaccination-Induced Antibody Responses to SARS-CoV-2 Variants of Interest and Concern

by Julia Svetlova, Dmitry Gustin, Valentin Manuvera, Dmitriy Shirokov, Varvara Shokina, Kirill Prusakov, Konstantin Aldarov, Daria Kharlampieva, Daria Matyushkina, Julia Bespyatykh, Anna Varizhuk, Vassili Lazarev and Tatiana Vedekhina

Int. J. Mol. Sci. 2022, 23(21), 13220; https://doi.org/10.3390/ijms232113220 - 30 Oct 2022

Cited by 4 | Viewed by 1793

Abstract

Mutations in surface proteins enable emerging variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to escape a substantial fraction of neutralizing antibodies and may thus weaken vaccine-driven immunity. To compare available vaccines and justify revaccination, rapid evaluation of antibody (Ab) responses to [...] Read more.

Mutations in surface proteins enable emerging variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to escape a substantial fraction of neutralizing antibodies and may thus weaken vaccine-driven immunity. To compare available vaccines and justify revaccination, rapid evaluation of antibody (Ab) responses to currently circulating SARS-CoV-2 variants of interest (VOI) and concern (VOC) is needed. Here, we developed a multiplex protein microarray-based system for rapid profiling of anti-SARS-CoV-2 Ab levels in human sera. The microarray system was validated using sera samples from SARS-CoV-2-free donors and those diagnosed with COVID-19 based on PCR and enzyme immunoassays. Microarray-based profiling of vaccinated donors revealed a substantial difference in anti-VOC Ab levels elicited by the replication-deficient adenovirus vector-base (Sputnik V) and whole-virion (CoviVac Russia COVID-19) vaccines. Whole-virion vaccine-induced Abs showed minor but statistically significant cross-reactivity with the human blood coagulation factor 1 (fibrinogen) and thrombin. However, their effects on blood clotting were negligible, according to thrombin time tests, providing evidence against the concept of pronounced cross-reactivity-related side effects of the vaccine. Importantly, all samples were collected in the pre-Omicron period but showed noticeable responses to the receptor-binding domain (RBD) of the Omicron spike protein. Thus, using the new express Ab-profiling system, we confirmed the inter-variant cross-reactivity of the anti-SARS-CoV-2 Abs and demonstrated the relative potency of the vaccines against new VOCs. Full article

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11 pages, 3005 KiB

Open AccessArticle

Betaine-Based Deep Eutectic Solvent as a New Media for Laccase-Catalyzed Template-Guided Polymerization/Copolymerization of Aniline and 3-Aminobenzoic Acid

by Irina Vasil’eva, Olga Morozova, Galina Shumakovich and Alexander Yaropolov

Int. J. Mol. Sci. 2022, 23(19), 11409; https://doi.org/10.3390/ijms231911409 - 27 Sep 2022

Cited by 4 | Viewed by 1530

Abstract

Deep eutectic solvents (DESs) can compensate for some of the major drawbacks of traditional organic solvents and ionic liquids and meet all requirements of green chemistry. However, the potential of their use as a medium for biocatalytic reactions has not been adequately studied. [...] Read more.

Deep eutectic solvents (DESs) can compensate for some of the major drawbacks of traditional organic solvents and ionic liquids and meet all requirements of green chemistry. However, the potential of their use as a medium for biocatalytic reactions has not been adequately studied. In this work we used the DES betaine-glycerol with a molar ratio of 1:2 as co-solvent for enzymatic template-guided polymerization/copolymerization of aniline (ANI) and 3-aminobenzoic acid (3ABA). The laccase from the basidial fungus Trametes hirsuta and air oxygen served as catalyst and oxidant, respectively. Sodium polystyrene sulfonate (PSS) was used as template. Interpolyelectrolyte complexes of homopolymers polyaniline (PANI) and poly(3-aminobenzoic acid) (P3ABA) and copolymer poly(aniline-co-3-aminobenzoic acid) (P(ANI-3ABA)) were prepared and their physico-chemical properties were studied by UV-Vis and FTIR spectroscopy and cyclic voltammetry. According to the results obtained by atomic force microscopy, PANI/PSS had a granular shape, P(ANI-3ABA)/PSS had a spherical shape and P3ABA/PSS had a spindle-like shape. The copolymer showed a greater antimicrobial activity against Escherichia coli and Staphylcocus aureus as compared with the homopolymers. The minimal inhibitory concentration of the P(ANI-3ABA)/PSS against the gram-positive bacterium S. aureus was 0.125 mg mL⁻¹. Full article

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12 pages, 489 KiB

Open AccessArticle

Molecular Characteristics, Receptor Specificity, and Pathogenicity of Avian Influenza Viruses Isolated from Wild Ducks in Russia

by Elizaveta Boravleva, Anastasia Treshchalina, Yulia Postnikova, Alexandra Gambaryan, Alla Belyakova, Galina Sadykova, Alexey Prilipov, Natalia Lomakina and Aydar Ishmukhametov

Int. J. Mol. Sci. 2022, 23(18), 10829; https://doi.org/10.3390/ijms231810829 - 16 Sep 2022

Cited by 4 | Viewed by 1669

Abstract

Avian influenza viruses (AIV) of wild ducks are known to be able to sporadically infect domestic birds and spread along poultry. Regular surveillance of AIV in the wild is needed to prepare for potential outbreaks. During long-year monitoring, 46 strains of AIV were [...] Read more.

Avian influenza viruses (AIV) of wild ducks are known to be able to sporadically infect domestic birds and spread along poultry. Regular surveillance of AIV in the wild is needed to prepare for potential outbreaks. During long-year monitoring, 46 strains of AIV were isolated from gulls and mallards in Moscow ponds and completely sequenced. Amino acid positions that affect the pathogenicity of influenza viruses in different hosts were tested. The binding affinity of the virus for receptors analogs typical for different hosts and the pathogenicity of viruses for mice and chickens were investigated. Moscow isolates did not contain well-known markers of pathogenicity and/or adaptation to mammals, so as a polybasic cleavage site in HA, substitutions of 226Q and 228G amino acids in the receptor-binding region of HA, and substitutions of 627E and 701D amino acids in the PB2. The PDZ-domain ligand in the NS protein of all studied viruses contains the ESEV or ESEI sequence. Although several viruses had the N66S substitution in the PB1-F2 protein, all Moscow isolates were apathogenic for both mice and chickens. This demonstrates that the phenotypic manifestation of pathogenicity factors is not absolute but depends on the genome context. Full article

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20 pages, 1978 KiB

Open AccessReview

Mechanochemical Transformations of Polysaccharides: A Systematic Review

by Tatiana A. Akopova, Tatiana N. Popyrina and Tatiana S. Demina

Int. J. Mol. Sci. 2022, 23(18), 10458; https://doi.org/10.3390/ijms231810458 - 09 Sep 2022

Cited by 3 | Viewed by 1748

Abstract

Taking into consideration the items of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), this study reviews application of mechanochemical approaches to the modification of polysaccharides. The ability to avoid toxic solvents, initiators, or catalysts during processes is an important characteristic [...] Read more.

Taking into consideration the items of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), this study reviews application of mechanochemical approaches to the modification of polysaccharides. The ability to avoid toxic solvents, initiators, or catalysts during processes is an important characteristic of the considered approach and is in line with current trends in the world. The mechanisms of chemical transformations in solid reactive systems during mechanical activation, the structure and physicochemical properties of the obtained products, their ability to dissolve and swell in different media, to form films and fibers, to self-organize in solution and stabilize nanodispersed inorganic particles and biologically active substances are considered using a number of polysaccharides and their derivatives as examples. Full article

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15 pages, 1343 KiB

Open AccessArticle

Effect of Mono- and Multichlorinated Organic Compounds—Chlorocyclohexane and Hexachloro-p-xylene—On the Catalytic Properties of Titanium–Magnesium Catalysts in the Homo- and Copolymerization of Ethylene with 1-Hexene

by Ildar I. Salakhov, Tatiana B. Mikenas, Vladimir A. Zakharov, Valeriy G. Kozlov, Mikhail A. Matsko and Tatiana N. Suslova

Int. J. Mol. Sci. 2022, 23(18), 10335; https://doi.org/10.3390/ijms231810335 - 07 Sep 2022

Cited by 1 | Viewed by 1260

Abstract

Ethylene polymerization and ethylene/1-hexene copolymerization over the titanium–magnesium catalytic system in the presence of chlorocyclohexane (CHC) and hexachloro-p-xylene (HCPX) has been studied. Modification of TMC with chlorocyclohexane and hexachloro-p-xylene increased catalyst activity severalfold for both ethylene polymerization and ethylene/1-hexene copolymerization. The key kinetic [...] Read more.

Ethylene polymerization and ethylene/1-hexene copolymerization over the titanium–magnesium catalytic system in the presence of chlorocyclohexane (CHC) and hexachloro-p-xylene (HCPX) has been studied. Modification of TMC with chlorocyclohexane and hexachloro-p-xylene increased catalyst activity severalfold for both ethylene polymerization and ethylene/1-hexene copolymerization. The key kinetic regularities of ethylene homopolymerization and ethylene/1-hexene copolymerization in the presence of CHC and HCPX were determined, and the copolymerization constants were measured. Molecular characteristics and the copolymer composition were determined for the synthesized samples of ethylene homopolymers and ethylene/hexene copolymers. Modification of the titanium–magnesium catalyst with chlorinated organic compounds reduced 1-hexene content in the copolymer; polymerization was sensitive to 1-hexene as a regulator of polymer molecular weight. The potential mode of action of chlorinated organic modifiers on catalytic properties of titanium–magnesium catalyst is discussed. Full article

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9 pages, 1312 KiB

Open AccessArticle

A Study of the Buffer Capacity of Polyelectrolyte Microcapsules Depending on Their Concentration and the Number of Layers of the Polyelectrolyte Shell

by Egor V. Musin, Alexey V. Dubrovskii, Aleksandr L. Kim and Sergey A. Tikhonenko

Int. J. Mol. Sci. 2022, 23(17), 9917; https://doi.org/10.3390/ijms23179917 - 31 Aug 2022

Cited by 4 | Viewed by 1336

Abstract

Polyelectrolyte microcapsules are used in the development of new forms of targeted delivery systems, self-healing materials, sensors, and smart materials. Nevertheless, their buffer capacity has not been practically studied, although that characteristic makes it possible to estimate the change in the state of [...] Read more.

Polyelectrolyte microcapsules are used in the development of new forms of targeted delivery systems, self-healing materials, sensors, and smart materials. Nevertheless, their buffer capacity has not been practically studied, although that characteristic makes it possible to estimate the change in the state of protonation of the entire polyelectrolyte system. This is necessary both for creating a buffer barrier system for pH-sensitive compounds (metals, enzymes, polyelectrolytes, drugs) and for the correct interpretation of the results of research and studying of the PMC structure. The buffer capacity of a PMC can be affected by the concentration of microcapsules in solution and the number of shell layers since the listed parameters affect other physicochemical properties of the PMC shell. This includes, for example, the electrical conductivity, permeability (of ions), osmotic pressure, charge density, etc. In this regard, we studied the change in the buffer capacity of polyelectrolyte microcapsules depending on their concentration and the number of shell layers. As a result, it was found that with an increasing concentration of microcapsules, the buffering capacity of the PMC increases, but at the same time, in the pH range from 4 to 5.5, the calculated buffering capacity of 1 billion capsules decreases with increasing their concentration. This effect may be associated with a decrease in the available -NH₂ groups of the PMC’s shell. In addition, it was found that the main contribution to the buffer capacity of a PMC is made by the entire shell of the microcapsule and not just its surface. At the same time, the buffer capacity of the capsules has non-linear growth with an increase in the number of PMC shell layers. It is presumably associated either with a decrease in the polyelectrolyte layer with an increase in their number or with a decrease in the permeability of hydrogen protons. Full article

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16 pages, 4389 KiB

Open AccessArticle

Water-Soluble Chalcogenide W₆-Clusters: On the Way to Biomedical Applications

by Alena D. Gassan, Anton A. Ivanov, Tatiana N. Pozmogova, Ilia V. Eltsov, Natalia V. Kuratieva, Yuri V. Mironov and Michael A. Shestopalov

Int. J. Mol. Sci. 2022, 23(15), 8734; https://doi.org/10.3390/ijms23158734 - 05 Aug 2022

Cited by 4 | Viewed by 1420

Abstract

Despite the great potential of octahedral tungsten cluster complexes in fields of biomedical applications such as X-ray computed tomography or angiography, there is only one example of a water-soluble W₆Q₈-cluster that has been reported in the literature. Herein we [...] Read more.

Despite the great potential of octahedral tungsten cluster complexes in fields of biomedical applications such as X-ray computed tomography or angiography, there is only one example of a water-soluble W₆Q₈-cluster that has been reported in the literature. Herein we present the synthesis and a detailed characterization including X-ray structural analysis, NMR, IR, UV–Vis spectroscopies, HR-MS spectrometry, and the electrochemical behavior of two new cluster complexes of the general formula W₆Q₈L₆ with phosphine ligands containing a hydrophilic carboxylic group, which makes the complexes soluble in an aqueous medium. The hydrolytic stability of the clusters’ aqueous solutions allows us to investigate for the first time the influence of W₆-clusters on cell viability. The results obtained clearly demonstrate their very low cytotoxicity, comparable to the least-toxic clusters presented in the literature. Full article

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15 pages, 2032 KiB

Open AccessArticle

Protease and DNase Activities of a Very Stable High-Molecular-Mass Multiprotein Complex from Sea Cucumber Eupentacta fraudatrix

by Anna M. Timofeeva, Irina A. Kostrikina, Pavel S. Dmitrenok, Svetlana E. Soboleva and Georgy A. Nevinsky

Int. J. Mol. Sci. 2022, 23(12), 6677; https://doi.org/10.3390/ijms23126677 - 15 Jun 2022

Cited by 1 | Viewed by 1427

Abstract

Only some human organs, including the liver, are capable of very weak self-regeneration. Some marine echinoderms are very useful for studying the self-regeneration processes of organs and tissues. For example, sea cucumbers Eupentacta fraudatrix (holothurians) demonstrate complete restoration of all organs and the [...] Read more.

Only some human organs, including the liver, are capable of very weak self-regeneration. Some marine echinoderms are very useful for studying the self-regeneration processes of organs and tissues. For example, sea cucumbers Eupentacta fraudatrix (holothurians) demonstrate complete restoration of all organs and the body within several weeks after their division into two parts. Therefore, these cucumbers are a prospective model for studying the general mechanisms of self-regeneration. However, there is no data available yet concerning biomolecules of holothurians, which can stimulate the processes of organ and whole-body regeneration. Investigation of these restoration mechanisms is very important for modern medicine and biology because it can help to understand which hormones, nucleic acids, proteins, enzymes, or complexes play an essential role in self-regeneration. It is possible that stable, polyfunctional, high-molecular-weight protein complexes play an essential role in these processes. It has recently been shown that sea cucumbers Eupentacta fraudatrix contain a very stable multiprotein complex of about 2000 kDa. The first analysis of possible enzymatic activities of a stable protein complex was carried out in this work, revealing that the complex possesses several protease and DNase activities. The complex metalloprotease is activated by several metal ions (Zn²⁺ > Mn²⁺ > Mg²⁺). The relative contribution of metalloproteases (~63.4%), serine-like protease (~30.5%), and thiol protease (~6.1%) to the total protease activity of the complex was estimated. Metal-independent proteases of the complex hydrolyze proteins at trypsin-specific sites (after Lys and Arg). The complex contains both metal-dependent and metal-independent DNases. Mg²⁺, Mn²⁺, and Co²⁺ ions were found to strongly increase the DNase activity of the complex. Full article

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9 pages, 1714 KiB

Open AccessArticle

A Study of the Buffer Capacity of Polyelectrolyte Microcapsules Depending on Their Ionic Environment and Incubation Temperature

by Alexey V. Dubrovskii, Aleksandr L. Kim, Egor V. Musin and Sergey A. Tikhonenko

Int. J. Mol. Sci. 2022, 23(12), 6608; https://doi.org/10.3390/ijms23126608 - 14 Jun 2022

Cited by 3 | Viewed by 1430

Abstract

Polyelectrolyte microcapsules (PMCs) are used in the development of new forms of drugs, coatings and diagnostic systems. Their buffer capacity, depending on the conditions of the medium, has not been practically studied, although it can affect the structure of both the capsule itself [...] Read more.

Polyelectrolyte microcapsules (PMCs) are used in the development of new forms of drugs, coatings and diagnostic systems. Their buffer capacity, depending on the conditions of the medium, has not been practically studied, although it can affect the structure of both the capsule itself and the encapsulated agents. In this connection, we studied the buffer capacity of polyelectrolyte microcapsules of the composition (polystyrene sulfonate/polyallylamine)₃ ((PSS/PAH)₃) depending on the concentration and the type of salt in solution, as well as the microcapsule incubation temperature. It was found that the buffer capacity of microcapsules in the presence of mono- and di-valent salts of the same ionic strength did not differ practically. Increasing the NaCl concentration to 1 M led to an increase of buffer capacity of PMCs at pH ≥ 5, and an increase in NaCl concentration above 1 M did not change buffer capacity. The study of the buffer capacity of pre-heated PMCs showed that buffer capacity decreased with increasing incubation temperature, which was possibly due to the compaction of the PMCs and an increase in the number of compensated PAH sites. The addition of 1 M sodium chloride to heated PMCs presumably reversed the process described above, since an increase in the ionic strength of the solution led to an increase of the buffer capacity of the PMCs. The effects described above confirm the hypothesis put forward that the buffer properties of microcapsules are determined by uncompensated PAH regions in their composition. Full article

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