The PM3/PM7 semi-empirical quantum-chemical methods were for the first time used to calculate and analyze the geometric configuration parameters of silicon analogs of the 20 proteinogenic L-amino acids. Enthalpies of formation and dipole moments were calculated along with conformational parameters. Bond lengths of the silicon analogs were shown to significantly exceed the bond lengths in the carbon amino acids. Intramolecular hydrogen bonding was found to be possible in the silicon analog of aspartate, like in carbon aspartate. The lowest thermodynamic stability was observed for aromatic and heterocyclic amino acid analogs. The role that an aromatic analog may play in silicon compounds differs from the respective role in carbon compounds as a result of longer interatomic distances and weaker π conjugation. A polyalanine chain model was used to demonstrate that the α-helical conformation corresponds to the global minimum of the heat of formation in both carbon and silicon peptides.

При помощи полуэмпирической квантово-химической методики PM3/РМ7 впервые рассчитаны и проанализированы геометрические особенности молекул кремниевых аналогов 20 протеиногенных L-аминокислот и проводится их сравнение с углеродными аминокислотами. Помимо конформационных параметров определены значения энтальпий образования и дипольных моментов изученных соединений. Показано, что длины связей в кремниевых аналогах аминокислот значительно превосходят длины связей в углеродных аминокислотах. В кремниевом аналоге аспартата (как и в углеродном аспартате) возможно образование внутримолекулярной водородной связи. Наименьшей термодинамической стабильностью характеризуются ароматические и гетероциклические аналоги аминокислот, причем вопрос ароматичности в кремниевых соединениях носит иной характер, нежели в соединениях углерода, из-за более длинных межатомных расстояний и более слабого пи-сопряжения. На модели полиаланиновой цепи показано, что как в углеродном, так и в кремниевом пептиде глобальный минимум теплоты образования такой молекулы соответствует конформации альфа-спирали.

В работе на основе полуэмпирических квантово-химических расчетов и докинга проанализировано конформационное многообразие изомеров природных и синтетических стероидов. Моделируется связывание различных изомеров и аналогов тестостерона с андрогенным рецептором. Особое внимание уделяется рассмотрению роли структурных и термодинамических факторов в определении предпочтительных изомеров тестостерона, обусловливающих, возможно, наилучшее обеспечение функционирования его комплекса с андрогенным рецептором.

The conformational diversity of isomers of natural and synthetic steroids was analyzed on the basis of semi-empirical quantum chemical calculations and docking. The binding of various isomers and analogues of testosterone to the androgen receptor was modeled. Special attention was paid to the role of structural and thermodynamic factors in determining the preferred isomers of testosterone that might determine the best functioning of its complex with the androgen receptor.

The possibility of observing the stimulated de-excitation of nuclear isomers (SDENI) in plasma (plasma lifetime ∼1.5 ps, temperature of electrons ∼ 10 keV) formed by the impact of a high-power laser pulse (∼10 18 W cm −2 ) on a target is studied experimentally. Preliminary experiments are carried out with the 110 m Ag ( T 1/2 = 250 days) and 186 m Re ( T 1/2 = 2 × 10 5 years) isomers. A weak SDENI effect is observed only for the 110 m Ag isomer on a platinum backing.

The influence of the stable sp3 hybrid structure of the valence amino group orbitals of nitrous bases on the initiation of the hidden structural polymorphism of the Watson–Crick base pairs is considered. The key role of differences in the polymorphism of the AT and GC pairs in the formation of structural and functional features of the genomic DNA is shown by the methods of computer chemistry and comparative genomics.

The advanced high performance computing methods are used to study the stability and conformational dynamics of the bacterial enzyme lipase LipA, its mutants, and the close homologous enzyme CLE whose substrate is polylactic acid-based plastics. From the analysis of the GPU molecular dynamics of native lipases and their mutants the amino acid residues whose point substitutions can markedly improve the thermostability of the enzymes under study without deteriorating their activity are determined.

This paper presents the optical layout and composition of a system for automatically adjusting the multipass power module of a next-generation laser apparatus. An adjustment technique based on near-field and far-field markers is described. A control program under the Astra Linux operating system is described for the automatic-adjustment system.

В работе с использованием методов сравнительной геномики обсуждается проблема неравноправия встречаемости АТ-и GC-пар в ДНК структуре генома человека.На фоне общего характера доминирования А/Т-треков в структуре целых хромосом обнаружено лимитирующее влияние минисателитных S(G/C)n-треков на формирования специфики GC-состава их экзонных областей.Полученные результаты позволили весь хромосомный набор генома человека систематизировать на III различных типа хромосом

The conditions and mechanisms of the immobilization of inulinase on polymeric carriers were studied using the VION KN-1 and KU-2 cation-exchangers, VION AN-1 and AV-17-2P anion-exchangers, and the ampholyte KOPAN-90. The calculated data showed a significant role of van der Waals interactions and hydrogen bonding in the formation of virtually all inulinase complexes with the immobilization matrices. The AV-17-2P anion-exchanger was the only one of the studied polymer matrices that was unable to form hydrogen bonds with inulinase. The mechanisms of the interaction between inulinase and various ampholytes and cation and anion exchange resins differ from each other. The strongest differences are observed in mechanisms of the sorption of inulinase on VION KN-1 and chitosan matrices. Approximately 87% of the identical amino-acid residues are involved in the interaction of the enzyme with the KU-2 and AV-17-2P resins and the VION AN-1 and KOPAN-90 fibers.

The comparative analysis of the frequency of oligomeric W- and S-tracts was conducted in the genomes of different eukaryotic species that differ in their GC-composition. The domination of mononucleotide and mixed (A/T) n -sequences compared with (G/C) n -sequences was detected in the studied eukaryotic genomes, including Dictyostelium discoideum (GC ~ 25.7%), Caenorhabditis elegans (GC ~ 36.9%), Arabidopsis thaliana (GC ~ 38.0%), Drosophila melanogaster (GC ~ 38.8%), Homo sapiens (GC ~ 40.0%), Gallus gallus (GC ~ 50.0%), Leishmania major (GC ~ 59.1%). Using the results of quantum–chemical calculations, a theoretical rationale of the important role of existing differences in the initial hidden structural polymorphism of the hydrogen bonding of the Watson–Crick AT and GC pairs in the development of this phenomenon is given. It is concluded that a decreased structural polymorphism of AT pairs compared with the high fourfold polymorphism of the main state of GC pairs may be the most probable source of the preference and reliability of the “use” of AT pairs by nature in genomic DNA of many species.

Using computer modeling, virtual screening of high-affinity ligands for immobilization of inulinase – an enzyme that cleaves inulin and fructose-containing polymers to fructose – has been performed. The inulinase molecule from Aspergillus ficuum (pdb: 3SC7) taken from the database of protein structures was used as a protein model and the target for flexible docking.The set of ligands studied included simple sugars (activators, inhibitors, products of enzymatic catalysis), as well as high-molecular weight compounds (polycation and polyanion exchange resins, glycoproteins, phenylalanine-proline peptide, polylactate, and caffeine). Based on the comparative analysis of the values of the total energy and the localization of ligand binding sites, we made several assumptions concerning the mechanisms of interaction of the suggested matrices for the immobilization of enzyme molecules and the structural features of such complexes. It was also assumed that the candidates for immobilization agents meeting the industrial requirements may be glycoproteins, for which we propose an additional incorporation of cysteine residues into their structure, aimed to create disulfide «anchors» to the surface.

The conformational diversity of the 20 DNA-encoded proteinogenic amino acids and their zwitterions in the gaseous state and in the state with the first hydration shell was analyzed using the PM3 and PM7 semi-empirical quantum-chemistry programs.

The objective of the present study was to elucidate the specific clinical features of otogenic intracranial complications (ICC) encountered in the current otorhinolaryngological practice. The work is based on the results of the retrospective analysis of 106 adult patients presenting with otogenic intracranial complications admitted for the treatment to multidisciplinary clinics of Sankt-Peterburg and Krasnoyarsk. Forty six (42.5%) patients presented with acute otitis media. 90% of them had suppurative destructive mastoiditis. In sixty (56.6%) patients, chronic suppurative otitis media (epitympanophonia) was associated with the extensive destructive process spreading toward dura mater of the medial and posterior cranial fossae and onto the sigmoid sinus. The prevalence of intracranial complications among the adult patients suffering from suppurative otitis media and treated in the otorhinolaryngological clinics amounted to 3.17%. The overall structure of otogenic intracranial complications was as follows: meningitis 42.5%, brain and cerebellum abscess 24.5%, suppurative meningoencephalitis 19.8%, sinus thrombosis 5.7%, epidural and subdural empyemas 4.7%, the combined suppurative brain lesions 2.8%. Systemic inflammatory response syndrome (sepsis) was diagnosed in 33 (31%) patients with otogenic ICC. The high intrahospital mortality rate among the patients with this condition (20.8%) is emphasized. The main causes of the fatal outcome in the patients with otogenic intracranial complications are supposed to be brain oedema with the concomitant development of dyslocation syndrome and sepsis.

We have investigated the effect of the laser spot shape on the spatial distribution of accelerated ions on the front and back sides of a thin target irradiated by a picosecond laser pulse having the intensity of (3-4) x 10(18) W cm(-2). Experimental data are compared with numerical calculations. It is shown that the spatial structure of the ion bunch on the front side of the target resembles the laser spot structure rotated by 90 degrees.

We propose a hypothesis that the T-cell receptor is a possible target of thymic hormones. We modelled the conformational dynamics of thymopentin and its structural variants in solution, as well as the interactions of these short peptides with the proposed molecular target. Thymopentin is a five-amino-acid fragment of the thymic hormone thymopoietin (residues 32 to 36) that reproduces the immunomodulatory activity of the complete hormone. Using molecular dynamics and flexible docking methods, we demonstrated high-affinity binding of thymopentin and its prospective mimetics with the T-cell receptor. The calculated biological activity spectra of thymopentin and its two promising modifications can be used in immunomodulatory activity screenings with live systems.