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Steroid-26-monooxygenases belong to the cytochrome P450 superfamily and function as part of three-component systems together with ferredoxins and ferredoxin reductases providing electron transport. The P450-dependent redox partners of the actinobacterial strain Mycolicibacterium smegmatis mc2155 were investigated. The genes encoding mycolibacterial ferredoxins (FdxD and FdxE) and ferredoxin reductases (FdrA and FprA) were overexpressed in E. coli cells. A scheme for isolation and purification of synthesized recombinant proteins using affinity chromatography was developed, resulting in electrophoretically homogeneous preparations. Spectral analysis of ferredoxin reductase showed absorption peaks characteristic of FAD-containing proteins. The reaction of cytochrome c reduction using recombinant proteins was carried out, demonstrating that FdxD, FdxE, FdrA, and FprA can act as components of electron transport from the reducing equivalents of NAD(P)H. [ABSTRACT FROM AUTHOR]

A plasmid containing the genes encoding a fungal 17β-hydroxysteroid dehydrogenase, which ca-talyzes the reduction of 17-oxo group, and a mycobacterial glucose-6-phosphate dehydrogenase, which promotes the recycling of the essential coenzyme NAD(P)H, was constructed. Its constitutive expression in well-studied Mycolicibacterium neoaurum strains made it possible to increase the yield of C-17 hydroxysteroids significantly. In particular, recombinant strains created on the basis of M. neoaurum VKM Ac-1815D and M. neoaurum NRRL B-3805 ΔkstD exhibited predominant accumulation of testosterone, while the strain based on M. neoaurum VKM Ac-1816D accumulated 1(2)-dehydrotestosterone and testosterone simultaneously. [ABSTRACT FROM AUTHOR]

Variation in the parameters of the positron annihilation lifetime spectra in pure water presubjected to freeze–thaw processes is studied. It is shown that in freshly defrosted water (at 1–2°С), the ortho-positronium lifetime and formation probability tend to the corresponding values in ice (near its melting point), and after about 10 h they reach the values corresponding to ordinary water at the same temperature. It indicates that no complete (at molecular level) defragmentation of the ice lattice occurs immediately after ice melting, and rigid ice-like clusters, in which positronium formation is also possible remain in the liquid phase for several hours. [ABSTRACT FROM AUTHOR]

Mycolicibacterium smegmatis mc2155 has been genetically modified to be used as a platform for the expression of heterologous cytochrome P450 monooxygenases by introducing deletions in the kshB and kstD genes that encode key stages of the steroid nucleus enzymatic degradation. Three sets of genetic constructs have been created for heterologous expression of the genes encoding P450 cytochromes CYP106A1 from Bacillus megaterium DSM319 and CYP106A2 from B. megaterium ATCC13368 in M. smegmatis mc2155 (ΔkshBΔkstD) cells. The recombinant plasmids contained monocistronic expression cassettes of cytochrome genes (pNS31 and pNS32), tricistronic cassettes of cytochrome genes together with cDNA copies of adrenodoxin and adrenodoxin reductase genes of the bovine adrenal cortex (pNS33 and pNS34), or monocistronic gene cassettes of chimeric cytochromes fused with the DNA sequence encoding the CYP116B2 reductase domain from the soil bacterium Rhodococcus sp. NCIMB 9784 (pNS35 and pNS36). The recombinant strains of mycolicibacteria were shown to selectively monohydroxylate androstenedione (AD) under growth conditions. The product was identified as 15β-hydroxyandrostenedione (15β-OH-AD) by mass spectrometry and 1H and 13C NMR spectroscopy. The maximum level of 15β-OH-AD production (17.3 ± 1.5 mg/L) was observed when using the recombinant M. smegmatis mc2155 (ΔkshBΔkstD) (pNS32) strain, which expresses a single cyp106A2 gene from B. megaterium ATCC13368. Host proteins of M. smegmatis mc2155 were shown to be capable of supplying electrons to heterologous cytochromes to support their hydroxylation activity. The results we obtained are of a priority character, expand the understanding of the hydroxylation of steroid compounds by bacterial cytochromes CYP106A1/A2, and are important for the creation of microbial strains for producing valuable hydroxysteroids. [ABSTRACT FROM AUTHOR]

New methods for testosterone production from phytosterol were developed based on its cascade two-stage transformation by actinobacteria Mycolicibacterium neoaurum VKM Ac-1815D and Nocardioides simplex VKM Ac-2033D. Efficient oxidation of the phytosterol side chain by M. neoaurum resulted in formation of the main and side products: androst-4-en-3,20-dione (AD) and androsta-1,4-dien-3,20-dione (ADD), respectively, which were subsequently converted to testosterone by N. simplex. The latter reaction was reversible and catalyzed by the membrane-associated 17β-hydroxysteroid dehydrogenase (17β-HSD) capable of both oxidation and reduction of androstendione at C17. Addition of glucose and limited aeration were found to be the key factors providing for a shift of the 17β-HSD activity towards reduction in whole N. simplex cells. Testosterone production from phytosterol was realized using two approaches: (i) based on M. neoaurum cells inactivation after phytosterol conversion and application of the resting N. simplex biomass for androstenedione reduction and (ii) based on sequential application of the two living cultures. Under optimized conditions, the total yield of testosterone from phytosterol (10 g/L) reached 53 mol %. The results exceeded those reported so far for cascade phytosterol bioconversion to testosterone and may be used as a basis for development of new biotechnologies for production of the valuable steroid compounds, intermediates in the synthesis of modern medical preparations. [ABSTRACT FROM AUTHOR]

Reaction of N- tert-butyl-1-aza-1,3-enynes with symmetrically substituted 2-mercaptobenzimidazoles in water-alcohol solutions afford 4 H-[1,3]thiazino[3,2- a]benzimidazol-4-ols. The structure of compounds obtained was proved by the H and C NMR spectroscopy and X-ray diffraction data. [ABSTRACT FROM AUTHOR]

The prospects for designing a universal liquid-scintillation spectrometric complex facility for versatile analytical applications based on various types of instrumentation were considered. The approach proposed allows qualitative and quantitative analyses of complex radionuclide mixtures with widely varying activity ratios of the components, for the most part, without labor-consuming radiochemical isolation. The promises and limitations of the approach implemented in this work using RadSpectraDec software were analyzed. [ABSTRACT FROM AUTHOR]

method for the synthesis of the previously inaccessible 3-pyridin-4-yl-1,2,4-triazolo[3,4- b]-1,3,4-thiadiazepines was developed. The X-Ray diffraction data for 8- tert-butyl-3-pyridin-4-yl-1,2,4-triazolo[3,4- b]-1,3,4-thiadiazepine are presented. [ABSTRACT FROM AUTHOR]

N9-Alkyl-7-(trimethylsilyl)-9 H-[1,3]-thiazino[3,2- e]purine-4,9-diamines were synthesized by reaction of 3-trimethylsilyl-2-propinal alkylimines with 8-mercaptoadenine in anhydrous DMF. DFT quantum-chemical calculations of isomeric forms of one of the reaction products were performed. [ABSTRACT FROM AUTHOR]

Presents a letter to the editor about reactions of phenylpropynal N-tert-butylimine with 4-amino-3-mercapto-1,2,4-triazole derivatives.