Kinetic model of excitatory synapse functioning with glutamate and N-acetylaspartylglutamate (NAAG) as neurotransmitters in a three-component system regarding neuroglial astrocytic cells and the glutamate carboxypeptidase (GCPII) enzyme has been developed. The biphasic nature of the process providing excitation amplification within the modeling framework is shown. The role of excitatory synapse intensity has been investigated. The role of NAAG for enhancing neuronal connectivity and the realization of cognitive function is shown. The mechanism of cognition control by influencing on the efficiency of mGluR3 metabotropic receptor functioning is dis-cussed. The role of GCPII inhibition as a method of improving cognitive functions is studied. Dynamic features of the glutamatergic system behavior in neurodegenerative diseases (Alzheimer's disease, dementia), schizophrenia, traumatic brain injury, and epilepsy, as a part of development of the kinetic model are analyzed. The positive role of GCPII inhibition with the NAAG level increase as an effective approach to neuropathology treatment is shown.

Methods for preparation of 5′-substituted spiropyrans, their chemical properties, and the effects of various factors on the relative stabilities of the spiropyrans and their isomeric merocyanine forms are examined, reviewed, and discussed.

In this paper, we consider the studies carried out by the authors aimed at developing new hybrid structures and methods for obtaining a family of photochromic labels capable of photocontrolled interaction with inorganic components, as well as the results of studying their photochromic behavior and the selectivity of complex formation processes. In this paper, special attention is devoted to the choice of the desired composition and structure of label molecules and the practical implementation of laboratory technology for the synthesis of a set of target compounds with specified optical parameters. The data obtained open up prospects for the use of a new generation of photochromes based on functionalized spiropyrans as new hybrid materials for the creation on their basis: metal detectors, components of photochromic systems, and prototypes of molecular electronics smart devices.

An experimental study of the dynamics of the BOLD (blood oxygen level dependent) signal by functional magnetic resonance imaging was carried out. It was found that the dynamic responses of the BOLD-signal, have a biphasic character. Through kinetic modeling methods, it was shown that the biphasic nature of the hemodynamic response is based on negative feedback, with Ca2+ pulse inhibited by vasodilation products (NO and prostaglandin). The effect of thermoheliox (inhalation of a mixture of helium and oxygen at 70 degrees C) on functional hemodynamics was studied. It was shown that preliminary inhalation of thermoheliox stimulates and prolongs hemodynamic impulses.

A kinetic model of the dynamics of a multipathway mechanism of neurovascular coupling induced by nerve impulses was constructed. The model calculations were compared with experimental data on the changes in the blood oxygen level dependent signal during sensory-motor and visual excitation before and after the use of the nonsteroidal anti-inflammatory drug indomethacin. The influence of the catalytic activity of key enzymes on the dynamics of the neurovascular response in the proposed model is shown. The multipathway mechanism of the biochemical reactions provides stability of the neurovascular coupling during various possible catalytic activities of the key enzymes in the process.

Exhaled breath condensate (EBC) is a promising object for biomarkers search as it contains compounds reflecting changes of biological processes caused by various respiratory diseases including COVID-19. Molecular hydrogen was recently discovered as a new effective antioxidant that can restore lung function after COVID-19. The effect of molecular hydrogen on lung function was studied by comparing EBC protein profiles before and after hydrogen therapy in volunteers who had recovered from COVID-19. Total 108 EBC samples were collected with RTube devices from recovered volunteers before and after hydrogen inhalation. The collecting tube was additionally rinsed with methanol. Peptides obtained after tryptic digestion were analyzed by LC-MS/MS using a nano-LC Dionex system coupled to tims TOF Pro (Bruker) tandem high-resolution mass-spectrometer located in Skoltech. Totally 478 proteins and 1350 peptides were revealed. It was shown that in EBC of the group after the hydrogen therapy, the concentration of structural and protective proteins increased significantly, as well as the average number of detected proteins increased by 15% (from 349 to 398), and the intensity of the 36 most common proteins increased ~3 times compared with the group, which did not receive the therapy. Dermcidin, an antibiotic and proteolytic protein, was found one of the most often found proteins in the group after therapy. Overall, mass spectrometry based analysis showed both quantitative and qualitative EBC proteome changes before and after the hydrogen therapy. This work was partially supported by the RFBR grant 18-29-09158 MK.

The work is devoted to modeling the elementary stages of the hydrolysis reaction in the active site of enzymes belonging to the class of cholinesterases — acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The study allowed to describe at the molecular level the effect of the polymorphic modification of BChE, causing serious physiolog ical consequences. Cholinesterase plays a crucial role in the human body. AChE is one of the key enzymes of the central nervous system, and BChE performs protective functions in the body. According to the results of calculations using the combined method of quantum and molecular mechanics (KM/MM), the mechanism of the hydrolysis of the native acetylcholine substrate in the AChE active center was detailed. For a series of ester substrates, a method for estimation of dependence of the enzyme reactivity on the structure of the substrate has been developed. The mechanism of hydrolysis of the muscle relaxant of succininylcholine BChE and the effect of the Asp70Gly polymorph on it were studied. Using various computer simulation methods, the stability of the enzyme-substrate complex of two enzyme variants with succinylcholine was studied.

Kinetic modeling of the behavior of complex chemical and biochemical systems is an effective approach to study of the mechanisms of the process. A kinetic model of coronaviral infection development with a description of the dynamic behavior of the main variables, including the concentration of viral particles, affected cells, and pathogenic microflora, is proposed. Changes in the concentration of hydrogen ions in the lungs and the pH -dependence of carbonic anhydrase activity (a key breathing enzyme) are critical. A significant result is the demonstration of an acute bifurcation transition that determines life or system collapse. This transition is connected with exponential growth of concentrations of the process participants and with functioning of the key enzyme carbonic anhydrase in development of toxic effects. Physical and chemical interpretations of the therapeutic effects of the body temperature rise and the potential therapeutic effect of "thermoheliox" (respiration with a thermolized mixture of helium and oxygen) are given. The phenomenon of "thermovaccination" is predicted, which involves stimulation of the immune response by "thermoheliox".

A kinetic model describing the pulse of increased oxygen concentrations and the subsequent changes in the concentration of N-acetylaspartate in the excited nervous tissue of the human brain in response to an external signal is presented. The model is based on biochemical data, a multistage and nonlinear dynamic process the BOLD signal and N-acetylaspartate. The existence of multiple steady states explains the triggering effect of the system. The inhibitory effect of the substrate is a necessary factor for the autostabilization of N-acetylaspartate. The kinetic model allows the dynamic behavior of previously unmeasurable metabolites, namely, products of the hydrolysis of N-acetylaspartate, such as acetic and aspartic acid, and glutamic acid to be predicted. Kinetic modeling of the BOLD signal and the subsequent hydrolysis of N-acetylaspartate provides information about the biochemical and dynamic characteristics of some pathological conditions (schizophrenia, Canavan disease, and the superexcitation of the neural network).

This work presents the historical aspect of the study of cholinesterases and the effects of their inhibition by organophosphorus compounds, which were carried out in the USSR and Russia, from the 1930s–1940s to the present.

Background. The paper discusses the use of a thermal helium-oxygen mixture (t-Не/О2 ), a novel technology, in treating patients with the 2019-nCoV acute respiratory disease (COVID-19) who develop life-threatening respiratory failure. Aim to evaluate the safety and efficacy of t-Не/О2 inhalation combined with standard therapy in the treatment of acute respiratory failure in patients with COVID-19. Materials and Methods. This was a single-center, randomized, prospective study of 70 patients with COVID-19. All patients were divided into two groups: in Group 1 (n = 38) patients received t-He/О2 in addition to the standard COVID-19 treatment; and in Group 2 (n = 32) patients were given the standard treatment in accordance with the Clinical Treatment Guidelines for patients with COVID-19, developed by the Ministry of Health of the Russian Federation. The male/female ratio was 18/20 in Group 1 and 18/14 in Group 2. The mean age of the patients in the study was 53.5 years (43; 62): 56 years (42; 64) in Group 1 and 52 years (43; 66) in Group 2. All patients had computed tomography (CT) signs of lung injury: ground-glass opacities and areas of consolidation. SARS-CoV-2 RNA was detected in 30 Group 1 patients and 28 Group 2 patients. The patients were matched by sex, age, body mass index (BMI), area of pulmonary involvement, and laboratory findings. All patients provided voluntary informed consent to participate in the study and signed a consent form. Results. Inhalation of thermal helium-oxygen mixture combined with standard therapy did not cause any procedure-related side effects in any of the patients. The following changes were observed in all patients: pO2 /FiO2 , SpO2 , and lymphocyte counts increased, C-reactive protein (CRP) levels decreased, and D-dimer and ferritin levels returned to normal. In Group 1 statistically significant changes in the above-mentioned parameters were seen within three days, while in Group 2 the same changes were observed between Days 7 and 10 of treatment. In Group 1 patients cleared SARS-CoV-2 within 4872 hours after initiation of inhalation, which was confirmed by polymerase chain reaction (PCR), and in Group 2 virus elimination was achieved within 72168 hours. Conclusion. The addition of inhalation of a thermal gas mixture of helium and oxygen (t-He/О2 ) to the standard therapy for patients with SARS-CoV-2 infection, CT signs of pneumonia (grades СT2 or CT3), and acute respiratory failure improves gas exchange, contributes to a more rapid virus elimination, and indirectly reduces inflammation.

“Biocleaners” or “bioscavengers” are biological objects (enzymes, catalytic antibodies) that are capable of binding and/or hydrolyzing organophosphorus compounds (OPC). Their use seems to be the most effective alternative to traditional antidotes to neutralize or detoxify OPC. The introduction of bioscavengers allows neutralizing toxicant molecules in the bloodstream before they reach their biological targets, thereby providing protection against poisoning. Bioscavengers of the first-generation neutralized OPC molecules by stoichiometrically binding to them. The safety and efficacy of human butyrylcholinesterase (BChE) for protecting against OPC poisoning has been shown. However, the stoichiometric neutralization of OPC requires the introduction of a huge amount of expensive biopharmaceuticals. Catalytic bioscavengers that hydrolytically neutralize OPC were introduced at a much lower dose to achieve the same degree of effectiveness. The most effective catalytic bioscavengers are enzymes. The most promising enzymes are artificial mammalian paraoxonase mutants and bacterial phosphotriesterases. However, studies of other enzymes, such as prolidases, oxidases, artificial mutants of cholinesterases and carboxyl esterases and catalytic antibodies are actively ongoing. Since OPC are pseudosubstrates of cholinesterases (ChEs), a detailed description of the mechanisms of inhibition, dealkylation, and spontaneous reactivation of phosphorylated ChEs is critical for the development of ChEs mutants with a high rate of hydrolysis of OPC. The review presents an analysis of different views on the mechanisms of interaction of ChEs with OPC, discusses the possible directions of creating effective catalytic biological traps based on BChE and changes in their mechanism of action as compared to the native enzyme. A separate section is devoted to the effect of mutations, both polymorphic and artificial, on the stability of the protein molecule of BChE.

The collective monograph is devoted to discussing the history of creation, studying the properties, neutralizing and using organophosphorus neurotoxins, which include chemical warfare agents, agricultural crop protection chemical agents (herbicides and insecticides) and medicines. The monograph summarizes the results of current scientific research and new prospects for the development of this field of knowledge in the 21st century, including the use of modern physicochemical methods for experimental study and theoretical analysis of biocatalysis and its mechanisms based on molecular modeling with supercomputer power. The book is intended for specialists who are interested in the current state of research in the field of organophosphorus neurotoxins. The monograph will be useful for students, graduate students, researchers specializing in the field of physical chemistry, physicochemical biology, chemical enzymology, toxicology, biochemistry, molecular biology and genetics, biotechnology, nanotechnology and biomedicine.

A kinetic model of the process response of nervous tissue to an external signal stimulus is proposed. The model is based on the multistage and non-linear nature of the dynamic process of changes of N-acetylaspartate concentration. The existence of multiple steady states explains the trigger effect of the system. The effect of substrate inhibition for this system was studied as a necessary factor of N-acetylaspartate’s autostabilization as a key metabolite in the brain. The appearance of N-acetylaspartate’s “anti-peak” causes a wave of its hydrolysis products, such as aspartic acid and acetic acid.

A computer-designed mutant of human butyrylcholinesterase (BChE), N322E/E325G, with a novel catalytic triad was made. The catalytic triad of the wild-type enzyme (S198·H438·E325) was replaced by S198·H438·N322E in silico. Molecular dynamics for 1.5 μs and Markov state model analysis showed that the new catalytic triad should be operative in the mutant enzyme, suggesting functionality. QM/MM modeling performed for the reaction of wild-type BChE and double mutant with echothiophate showed high reactivity of the mutant towards the organophosphate. A truncated monomeric (L530 stop) double mutant was expressed in Expi293 cells. Non-purified transfected cell culture medium was analyzed. Polyacrylamide gel electrophoresis under native conditions followed by activity staining with BTC as the substrate provided evidence that the monomeric BChE mutant was active. Inhibition of the double mutant by echothiophate followed by polyacrylamide gel electrophoresis and activity staining showed that this enzyme slowly self-reactivated. However, because Expi293 cells secrete an endogenous BChE tetramer and several organophosphate-reacting enzymes, catalytic parameters and self-reactivation constants after phosphorylation of the new mutant were not determined in the crude cell culture medium. The study shows that the computer-designed double mutant (N322E/E325G) with a new catalytic triad (S198·H438·N322E) is a suitable template for design of novel active human BChE mutants that display an organophosphate hydrolase activity.

Comprehensive studies of the effects of prolonged exposure to space conditions and the overload experienced during landing on physiological and biochemical changes in the human body are extremely important in the context of planning long-distance space flights, which can be associated with constant overloads and various risk factors for significant physiological changes. Exhaled breath condensate (EBC) can be considered as a valuable subject for monitoring physiological changes and is more suitable for long-term storage than traditional monitoring subjects such as blood and urine. Herein, the EBC proteome changes due to the effects of spaceflight factors are analyzed. Thirteen EBC samples were collected from five Russian cosmonauts (i) one month before flight (background), (ii) immediately upon landing modules in the field (R0) after 169-199 days spaceflights, and (iii) on the seventh day after landing (R+7). Semi-quantitative label-free EBC proteomic analysis resulted in 164 proteins, the highest number of which was detected in EBC after landing (R0). Pathways enrichment analysis using the GO database reveals a large group of proteins which take part in keratinization processes (CASP14, DSG1, DSP, JUP, and so on). Nine proteins (including KRT2, KRT9, KRT1, KRT10, KRT14, DCD, KRT6C, KRT6A, and KRT5) were detected in all three groups. A two-sample Welch's t-test identified a significant change in KRT2 and KRT9 levels after landing. Enrichment analysis using the KEGG database revealed the significant participation of detected proteins in pathogenic E. coli infection (ACTG1, TUBA1C, TUBA4A, TUBB, TUBB8, and YWHAZ), which may indicate microbiota changes associated with being in space. This assumption is confirmed by microbial composition analysis. In general, the results suggest that EBC can be used for noninvasive monitoring of health status and respiratory tract pathologies during spaceflights, and that the obtained data are important for the development of medicine for use in extreme situations. Data are available from ProteomeXchange using the identifier PXD014191.

The monograph consists of reviews prepared by specialists having scientific publications, theoretical knowledge and practical experience in research of immobilized cells of different microorganisms, plants and animals, which they conducted for the last decade. The basis of the reviews is composed by the scientific results of the authors and relevant data on the discussed topics, presented in the modern world literature. The monograph collected information about the characteristics of immobilized cells, various approaches used to their regulation, the possible long-term functioning and storage of such cells. It performs the prospects for application of immobilized cells in biomedicine, biodetection systems, synthetic processes of biologically active substances and in overcoming environmental problems. The monograph is intended for specialists in the field of biotechnology, heterogeneous catalysis, green chemistry, biochemistry, biophysics, ecology, cytology, biomedicine as well as for teachers and students of natural science and technological faculties of higher educational institutions, for anyone interested in new results of research on the properties of various cells and applied aspects of their possible use.

Hydrolysis of N-acetylaspartate (NAA), one of the most concentrated metabolites in brain, catalyzed by human aspartoacylase (hAsp) shows a remarkable dependence of the reaction rate on substrate concentration. At low NAA concentrations, sigmoidal shape of kinetic curve is observed, followed by typical rate growth of the enzyme-catalyzed reaction, whereas at high NAA concentrations self-inhibition takes place. We show that this rate dependence is consistent with a molecular model, in which N-acetylaspartate appears to have three faces in the enzyme reaction, acting as activator at low concentrations, substrate at moderate concentrations, and inhibitor at high concentrations. To support this conclusion we identify binding sites of NAA at the hAsp dimer including those on the protein surface (activating sites) and at the dimer interface (inhibiting site). Using the Markov state model approach we demonstrate that population of either activating or inhibiting site shifts the equilibrium between the hAsp dimer conformations with the open and closed gates leading to the enzyme active site buried inside the protein. These conclusions are in accord with the calculated values of binding constants of NAA at the hAsp dimer, indicating that the activating site with a higher affinity to NAA should be occupied first, whereas the inhibiting site with a lower affinity to NAA should be occupied later. Application of the dynamical network analysis shows that communication pathways between the regulatory sites (activating or inhibiting) and the gates to the active site do not interfere. These considerations allow us to develop a kinetic mechanism and to derive the equation for the reaction rate covering the entire NAA concentration range. Perfect agreement between theoretical and experimental kinetic data provides strong support to the proposed catalytic model.

A complex study of nonpolluting energy-and resource-saving processing of renewable feedstock with production of methane, ethanol, monosac-charides, biodiesel, and its light analogues is a base for a new technology with multipurpose use of biomass for producing valuable materials for fuel production. Biocatalytic processes with specialized microbe associations play an important role in processing carbohydrate raw materials from agricultural and woodworking wastes, such as straw, sawdust, etc. Biocatalytic methanogenesis is the most widely known process already implemented in practice. This process is complicated by generating additional organic compounds: ethanol, volatile fatty acids (VFAs)-acetic, propionic, butyric acids-toxic for microorganisms generating methane. This undesirable trend has triggered an alternative bioprocess aimed at obtaining the methanogenesis byproducts. A selection of microorganisms producing ethanol and VFA was carried out, pH and temperature conditions optimal for their functioning were determined, and the influence of these parameters on the yield and the ratio of biosynthesis products were studied.Ethanol and VFA are in a low-concentration water solution state during the bioprocess, thus, their extraction method is needed. The best results are obtained by common extraction of ethanol and VFA by halogenated hydrocarbons. This is explained by the generation of ethanol-VFA complexes, more lipophilic than the individual alcohol, the latter being practically impossible to extract from water solutions.Traditional methods of acid esterification by alcohols include using homogeneous or heterogeneous acid catalysts. Both variants have a number of limitations related to a ratio of reagents, process duration, catalyst type and cost, its removal from reaction sphere, and product purification. Alternative approaches minimizing these problems are being developed in the world. Recently, supercritical fluid (SCF) techniques have gained much attention. Application of SCF considerably enables, up to minutes, reduction in process time, dispenses with the catalyst, and, finally, reduces the total energy consumption.