Vol 68, No 6 (2023)

Electron paramagnetic resonance spectroscopy (EPR) and quantum chemical calculations based on density functional theory were used to demonstrate that the earlier observed changes in the EPR spectra of Tiron semiquinone radical dissolved in sea water solution occur due to interaction of Mg²⁺ ions with Tiron radical. This interaction is caused by electrostatic attraction between Mg²⁺ ions and Tiron radicals, which bears great charges of opposite sign (+2 and -3), on the one hand, and due to the ability of Mg²⁺ ion to bind to bidentate oxygen-containing ligands efficiently, on the other hand. The formation of tight contact ion pairs leads to electron and spin density redistribution in the Tiron radical, as can been seen by the observed changes in the EPR spectra of the radical.

By the method of the theoretic conformational analysis the conformational capabilities of the soymorphin-6 (Tyr1-Pro2-Phe3-Val4-Val5-Asn6-NH2) molecule were studied. The potential energy of this molecule is given as the sum of nonvalent, electrostatic and torsional interactions and the energy of hydrogen bonds. Low-energy conformations of the soymorphin-6 molecule, the values of the dihedral angles of the main and side chains of amino acid residues that make up the molecules are found, the energy of intra- and inter-residual interactions is estimated. It is shown that the spatial structure of the soymorphin-6 molecule can be represented by eight conformations. The results obtained can be used to study the structure and structural-functional organization of the soymorphin molecules.

Beta-bends are a difficult to interpret type of polypeptide chain backbone structure of globular proteins. Beta-bends are usually classified according to the dihedral angles φ and ψ of amino acid residues i + 1 and i + 2. Ramachandran map analysis of amino acid residues i + 1 and i + 2 indicates the resulting conformational stresses in bending. The mechanism of stabilization of their energetically disadvantageous conformations is still unclear. This kind of conformation stresses can only be compensated by additional interactions, such as additional hydrogen bonds, whose geometry and energy compensates for the beta-bending stress. Neutronography is the only available direct method for determining the position of hydrogen atoms in the structures of chemical compounds, including proteins. In this work, beta-bends from 176 protein structures from PDB established by neutronography are studied. In these structures, 3733 beta-bends were found using the i → i + 3 hydrogen bonding criterion. Using clustering by the magnitude of conformational angles, eight types of bends were newly identified. The magnitudes of conformational angles for each type of bend were determined. The hypothesis of additional hydrogen bonding to stabilize the bend was not confirmed, suggesting that the bending stress is compensated by other factors.

The mathematical study of the fluorescence action spectrum of photosynthesis was performed. The calculation of typical spectra for photosynthesis was done for the red and blue frequencies. The transition of the action spectrum of photosynthesis from wavelengths to the frequency scale was completed. A numerical method based on the use of the inverse Fourier transform approach was used to obtain a relaxation curve for the impulse (time) characteristic of fluorescence. It turned out that the radius vector of the module of impulse response in polar coordinates makes one half-turn or half of the period of light oscillations in time. It was established that the optical medium of a plant during the relaxation time has a negative space charge of electrons, inverse properties and properties of the coherent radiation. The condition of neutrality of the material environment is not met. It was found that the ratio of the variable chlorophyll fluorescence for red and blue light has almost the same value. An analysis of the dependence of the quality factor of the chlorophyll spectrum on frequency shows that the fluorescence energy loss in blue light significantly exceeds the energy loss in red light. The proposed method can be used for express analysis of the intensity of photosynthesis. It was also concluded that plants can emit ultra-wideband signals. The relaxation time of chlorophyll fluorescence is shorter than the relaxation time of electronic polarization in atoms (molecules). As a result, a population inversion is created in the optical medium of chlorophyll - there are more atoms in the upper energy level than in the lower level. Due to this, stimulated emission and amplification of light of the radiative recombination occur. In this case, the emission of fluorescence light becomes coherent. All these properties of plants are considered for the first time and have not been described either in domestic or in foreign articles.

This study shows that the background formation of lower levels of reactive oxygen species in mouse peritoneal neutrophils after short-term (40 minutes) exposure to hypomagnetic fields with ~10 nT residual field at physiological temperatures, which has been detected by use of lucigenin-dependent chemiluminescence, is not accompanied by the impairment of chemiluminescence response of neutrophils to respiratory-burst stimuli: the formylated tripeptide N-formyl-Met-Leu-Phe (fMLF) and phorbol ester phorbol-12-myristate-13-ace-tate (PMA). These results were obtained with lucigenin or luminol-enhanced activated chemiluminescence and various combinations of reactive oxygen species production stimuli (phorbol-12-myristate-13-acetate and/or N-formyl-Met-Leu-Phe). Based on the results of the present work as well as on those of previous studies, this study reveal that the systems that control the respiratory burst in neutrophils can be excluded from a list of main targets and acceptors that respond to short-term deprivation of the magnetic field.

The activity of lipolytic enzymes was assessed using the microplate method using heteromolecular exchange in soils from the bottom of burial vessels, followed by cluster analysis. Groups with a contrasting ratio of lipases C12 - C18 and esterases C4 - C8 were identified in a sample that included 57 burial pots aged two to three thousand years. The total lipolytic activity of soil samples from dishes with the presumptive initial presence of fat-containing food products was above 6% of the maximum value within the sample. Inhibition of esterases in the presence of high concentrations of fatty acids is reflected in the extremely low relative values of esterase activity of the soil microbial community against the background of maximum activity levels of C18 and C12 lipases in two groups of pots. In three groups, esterase activity was observed against the background of high relative activity of C16 lipases, average relative activity of C18 lipases and extremely low activity of true lipases. In the group of pots with high total lipolytic activity (with the exception of certain extreme values of this indicator), the proportion of true lipase activity was 1.7-1.8 times higher compared to the proportion of esterase activity. The grouping of burial vessels by the ratio of lipase and esterase activity reflects the characteristics of the funeral food, while the absolute values of enzyme activity among selected vessels with the highest total lipolytic activity are grouped according to the type of burial.

Using the method for calculating the average of conditional probabilities of recurrence intervals, a comparative analysis was performed to estimate the direction of coupling between different physiological rhythms in the form of fluctuations in blood pressure, respiration, and the activity of neurons in the reticular formation of the medulla oblongata in two groups of anesthetized rats under pain stimulation or no stimulus. It was found that there are different kinds of the directions of coupling between the analyzed rhythms. Most of the data obtained for rats from the control group and rats with experimentally induced colitis suggest the statistically significant unidirectionality of coupling. Painful stimulation did not affect the direction of coupling, but the amount of data on unidirectionaity of coupling slightly reduced. At the same time, the rhythms associated with the cardiovascular system (blood pressure variability) were controlled by the rhythms of the respiratory system, and the respiratory rhythm controlled the variability of the activity of neurons in the reticular formation of the medulla oblongata.

Biosensor systems are improving swiftly and become increasingly important in areas such as defense and security, medical field, especially, cancer screening and detection, environmental quality monitoring, and so forth. The present work describes the development of a biosensor system, based on the use of macrosmatic animal olfactory bulb (OB) visualized by optical imaging of odor-evoked glomerular activity patterns. The difficulties that automatic detection of odor-evoked patterns presents under multiple stimulation are associated with adaptation processes, which are manifested as a reversible change in the sensitivity of the neural structures of the olfactory system. The optimal stimulus duration and interstimulus intervals for stabilizing the glomerular response and getting images of glomerular activity patterns under the multiple odor stimulation with constant accuracy have been experimentally found. The results obtained show the availability of other resource in addition to the existing tools used for the development of biosensor systems.

The reason has been elucidated why gaseous nitric oxide inhalation does not produce hypotensive effect in human and animal organisms. The defect was completely removed when low molecular thiol solutions were added by intravenous pathway simultaneously with gaseous NO inhalation into the animals (rats). The proposition was made that gaseous NO molecules including through the lungs into the circulation of the blood are transformed as a result of one-electron mechanism oxidation into nitosonium cation (NO+) which are not capable of vasodilating and thereby hypotensive action on men and animals. NO+ cation binding with low molecular thiols results in the S-nitrosothiol (RS-NO) formation with following release of the nitrosyl component from the RS-NO in the form of neutral NO molecule characterized with hypotensive activity. The formation of another NO donor - dinitrosyl iron complexes with thiol-containing ligands did not occur in the animals. Hypotensive action observed in lungs could be determined by gaseous NO penetration trough external vascular wall followed by the activation of vasodilation and hypotensia inductor - guanylate cyclase enzyme immediately inside of vascular walls.

This paper expounds how to apply in practice the developed computer method of arterial piezopulsometry, with examples, for non-invasive express analysis of the functional state and the nature of autonomic regulation of the cardiovascular system in patients of different ages and health conditions. The participation and role of the contractile component of myocytes of the left ventricle of the heart is assessed as a universal muscle effector, providing both the basic pumping function of the heart and the implementation of the autonomic regulation of heart contraction using peripheral neurohumoral mechanisms that maintain the optimal level of cardiac hemodynamics. This analysis enhances the predictive value of early non-invasive pulsometric diagnostics of the individual functional state and nature of regulation of human cardiovascular system during ontogenesis. This knowledge helps identify the risk of reducing the ability of the cardiovascular system, which has developed during its evolution, to maintain dynamic balance, self-regulation and adaptation to changing environmental conditions, which is associated with a violation of the body’s homeostasis.

The process of amyloid aggregation is quite complex and poorly understood. In this work, having summarized previously obtained results on the aggregation of the multidomain smooth muscle protein titin, an attempt has been made to expand understanding of this process, and a new possible mechanism by which amyloid aggregation of titin may occur is delineated. Our main conclusion is that the ability of titin to form amorphous aggregates seems to be the only possible way of aggregation of this protein. Most likely, only separate parts of the molecules, but not the whole protein, are involved in the formation of the amyloid structure in amorphous aggregates of smooth muscle titin. This feature, given the large size of the protein molecule, distinguishes titin from other amyloid or amyloid-like proteins. The paper discusses the potential energy landscape underlying the formation of titin amyloid aggregates.