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Using chromatography, the gas composition in a cold plasma jet, which is a flowing afterglow of a microwave glow discharge at atmospheric pressure, is analyzed. The plasma jet is formed by the interaction of the discharge plasma with atmospheric air behind the outlet of the 6-electrode plasma torch, electrical power to which is supplied from the waveguide microwave (2.45 GHz) plasmatron. An analysis of the gas samples of the jet shows that when plasma-forming argon flows through the microwave discharge, hydrogen and methane are formed behind the discharge region, and the concentration of carbon monoxide increases by 5–6 times. The reactive oxygen species in the cold plasma jet is studied using liquid chromatography of an aqueous solution of isopropyl alcohol after treatment with the plasma jet. It is found that because of plasma treatment, partial oxidation of isopropyl alcohol to acetone occurs. This makes it possible to consider acetone as an indicator of reactive oxygen species (hydroxyl radicals, atomic oxygen and ozone) in a cold plasma jet. [ABSTRACT FROM AUTHOR]

Crystals of the enzyme purine nucleoside phosphorylase from the extremophilic bacterium Halomonas Chromatireducens AGD 8-3, suitable for X-ray diffraction, were grown by the vapor-diffusion method. The X-ray diffraction data were collected from these crystals at the Belok beamline of the Kurchatov synchrotron radiation source (National Research Centre "Kurchatov Institute") at 100 K to 1.80 Å resolution. The X-ray diffraction data were processed in the space groups P1, P2, P21, and P622. The structure was solved by the molecular replacement method taking into account the twinning in the space groups P21 and P1 with one and two hexamers of the enzyme per asymmetric unit, respectively. [ABSTRACT FROM AUTHOR]

The atmospheric-pressure cold plasma jet that is a flowing afterglow of the interelectrode microwave discharge in Ar was investigated using various diagnostic techniques. Waveguide-type 2.45-GHz-plasmatron with the external 6-rod-electrode plasma torch was used as the cold plasma source. High-speed shadowgraphy was used to obtain spatio-temporal structure of the cold plasma jet. The periodic character of plasma generation was studied using electric probe floating potential measurements with an oscilloscope. [ABSTRACT FROM AUTHOR]

Mutant uridine phosphorylase genes from Shewanella oneidensis MR-1 (S. oneidensis) were constructed by site-directed mutagenesis and strains-producers of the corresponding recombinant (F5I and F5G) proteins were obtained on the basis of Escherichia coli cells. The mutant proteins were purified and their physicochemical and enzymatic properties were studied. It was shown that the N-terminal fragment of uridine phosphorylase plays an important role in the thermal stabilization of the enzyme as a whole. The role of the aminoacid (a.a.) residue phenylalanine (F5) in the formation of thermotolerance of uridine phosphorylases from gamma-proteobacteria was revealed. [ABSTRACT FROM AUTHOR]

Observational data from the submesoscale hydrological polygon confirm the presence of summer runoff of dense Antarctic shelf water (ASW) on the continental slope in the Commonwealth Sea. It is provided by a huge amount of ASW accumulated in shelf depressions during winter. The ASW overflows the shelf edge in the form of discrete meanders, which are formed as a result of baroclinic instability of a deep ( 150–250 m) ASW front. The estimated instability scale along the dense water front km coincides with the observed spatial discreteness of ASW. At the same time, the distribution of near-bottom density currents affected by the bottom irregularities, is noted on the shelf. The Antarctic Slope Front (ASF) is formed on the slope due to the interaction of ASW with warm Circumpolar Deep Water (CDW). Due to the continuity of motion in the near-slope area, 3D cascading is accompanied by compensatory upwelling of CDW, which complements its large-scale advection. These processes form the intrusive structure of water on the edge of the shelf and on the shelf. Depending on the bathymetric characteristics of the slope in different parts of the polygon, the cascading of ASW has a different regime. [ABSTRACT FROM AUTHOR]

Orthovanadate was shown to serve as a substrate for nucleoside phosphorylases from Escherichia coli, Shewanella oneidensis, Geobacillus stearothermophilus, and Halomonas chromatireducens AGD 8-3. An exception is thymidine phosphorylase from the extremophilic haloalkaliphilic bacterium Halomonas chromatireducens AGD 8-3, which cannot catalyze the vanadolysis of nucleosides. The kinetic parameters of nucleoside vanadolysis were evaluated. [ABSTRACT FROM AUTHOR]

The promising development of the smart electric power industry is based on the use of functional materials created based on the latest achievements in science and technology. The properties of intelligent materials change when exposed to any external factors. The ability of such materials to convert one type of energy into another and the ability to control this conversion make it possible to create various sensors and actuators for performing complex functions that are widely used in the electric power industry. This review article considers the use of superconductors to improve the characteristics of electrical equipment for energy purposes and shows the obvious advantages of high-temperature superconducting cable lines, as well as the high-temperature superconductivity of transformers and electrical machines. All the intelligent materials, the introduction of which into the composition of high-voltage insulation allows us to control its quality during operation, and materials that start the process of the self-healing of the insulation when microcracks appear, as well as the optimal microstructures of hard magnetic materials in various temperature modes, are presented. [ABSTRACT FROM AUTHOR]

A library of strains producing recombinant nucleoside phosphorylases (NPs) and their mutant and hybrid forms from various mesophilic and extremophilic microorganisms was constructed based on Escherichia coli cells. Substrates were shown to stabilize the NP structure upon thermal exposure, with the inorganic phosphate ion playing a decisive role in the process. Bioinformatics analyses made it possible to assume that the N‑terminal structure of NPs is largely responsible for their thermal stability. A hybrid thymidine phosphorylase (TPP) was constructed via the replacement of the N-terminal fragment (amino acid residues 1–62) of E. coli TPP with the corresponding TPP fragment from the thermophilic bacterium Geobacillus stearothermophilus. Higher thermal stability was observed for the hybrid TPP. The primary structure of E. coli uridine phosphorylase (UDP) was found to have a sequence, 25-Pro-Gly-Asp-Pro-30 (amino acid residues are numbered as in E. coli UDP), that is highly conserved among UDPs of mesophilic microorganisms. The E. coli UDP (Asp27Gly) mutant was constructed and similarly showed a higher thermal stability than the original form. The architecture of the phosphate-binding site and features of its function were assumed to be crucial for the thermal stability of the enzyme. [ABSTRACT FROM AUTHOR]

Thymidine phosphorylase (deoA) and purine nucleoside phosphorylase (deoD) genes from the extremophilic bacterium Halomonas chromatireducens AGD 8-3 have been cloned. Expression plasmids were constructed, and highly efficient recombinant producer strains were obtained for these proteins. Recombinant nucleoside phosphorylases were isolated by ion-exchange chromatography in a homogeneous state, and their physical and enzymatic properties were studied. It was shown that the studied thymidine phosphorylase (HrTPP) and purine nucleoside phosphorylase (HrPNP) form the dimeric and hexameric forms, respectively. It was shown that the specific activity of HrTPP from the extremophilic bacterium H. chromatireducens AGD 8-3 was higher relative to thymidine (in comparison with its counterpart from E. coli). [ABSTRACT FROM AUTHOR]

Actual in situ observations at the Antarctic continental slope performed with eddy-resolving spatial resolution were used. As a result, some parameterizations were verified that describe the processes of instability of density flows on a sloping bottom derived during the laboratory experiments. These processes were identified based on observational data. Any changes in the bottom slope (local or general, linked to the transition of the steep slope into the deep-sea floor) lead to changes in the regime of dense water runoff. The resulting hydraulic jumps lead to the turbulent mixing and function as one of the main mechanisms of ventilation of deep and bottom water. In the areas of local bottom rubs, disturbances like leeward waves are sometimes observed at the dense water top. They cause the intrusive layering and subsequent occurrence of turbulence centers in the slope area; the eddy lenses which also take part in the slope water ventilation are sometimes observed over bottom rubs. A strong baroclinity of the Antarctic slope front (ASF) in a steep part of the slope is another mechanism of deep water ventilation. It leads to the instability of cascading, subsequent intrusive layering and eddy formation. The baroclinic instability is amplified by the increased dynamics of dense water runoff at the bottom slope increase. However, the realization of shear instability at density interface is possible but at the smaller spatial scale than the instability scales observed in the ASF area. [ABSTRACT FROM AUTHOR]

The developed approach to the calculation and construction of adequate local and common fields of potential density for the whole continental slope (to 2000 m) allows the representative detailed analysis of the downflow of cold and dense shelfwaters in all parts ofthe slope (cascading) in the Commonwealth Sea including the poorly explored deep part. Most often the slope cascading is manifested in the form of discrete meanders (in the steep part of the slope) or discrete plumes (both in the steep and deep parts). More rarely, it occurs in the form of intrusions and eddies (lenses). The pattern and stability of cascading depend on the slope steepness. The detected local irregularities of bottom topography also affect the cascading: they lead to the instability of density flows, intrusive layering, and eddy formation. [ABSTRACT FROM AUTHOR]

The possibilities of using metal glasses for magnetic cores of high-speed miniturbogenerators with a rotation frequency of up to 100000 rpm are studied. The existing amorphous and nanocrystalline alloys satisfying the requirements for designing miniturbogenerators are anlayzed. A numerical experiment is performed, demonstrating that the use of the domestic amorphous GM-440V alloy provides the possibility to halve the weight of the generator and increase its efficiency by 2%. Domestic nanocrystalline alloys are not inferior to foreign alloys in terms of their characteristics; however, they do not have sufficiently high values of the saturation magnetic flux density for use in magnetic cores. [ABSTRACT FROM AUTHOR]

Complex (dusty) plasmas of micron-sized CeO2 polydisperse particles in dc glow discharges at 77 and ∼ 10 K were experimentally investigated. It was obtained that dust structure in cryogenic gas discharge plasma can be a mixture of two fractions (components) with completely different dust ordering and dynamics. We observed under some specific conditions that fast-moving particles of one component diffuse through another component consisted of dust particles arranged in linear chains (strings). From experimental data analysis particle velocity distribution functions for each dust component were obtained. The possible nature of two-component dust structure formation was discussed. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Abstract: New small cytochrome c (TniCYT) was purified from haloalkaliphilic sulfur-oxidizing bacterium Thioalkalivibrio nitratireducens. The protein was analyzed by mass spectrometry as well as using visible, CD and EPR spectroscopy. It was found that TniCYT is a monomer with a molecular mass of 9461 Da which contains two hemes per molecule. The data of CD and EPR spectroscopy showed that two hemes possess different optical activity and are in distinct, high and low spin states. TniCYT was also demonstrated to have unusual characteristics in the visible spectrum, namely, the splitting of characteristic peaks was observed in α- and β-bands of the heme spectrum when the reduced form of cytochrome was analyzed. The α-band has two peaks with maximum at 548 and 556 nm whereas the β-band showes ones at 520 and 528 nm. According to the MALDI finger-print analysis, the new cytochrome has a unique amino acid sequence. [Copyright &y& Elsevier]

A dusty plasma in a dc gas discharge is considered at low (cryogenic) temperatures of the gas. The formation of dusty plasma structures consisting of monodisperse poly(styrene) particles ( d = 5.44 μm) in a dc glow discharge is experimentally investigated at cryogenic temperatures in the range from 4.2 to 77 K, and the results obtained are presented. The ion velocity distribution function and the charging of dust particles at cryogenic temperatures are calculated using the molecular dynamics method. The primary attention is focused on the correct inclusion of ion-atom collisions in the analysis. This is essential to the understanding of the main mechanisms of the experimentally observed increase in the density of dust particles with decreasing temperature of the gas in the discharge. [ABSTRACT FROM AUTHOR]

Results are given of experimental investigations of dust structures of monodisperse particles in a low-pressure dc glow discharge at temperatures of liquid nitrogen (T=77 K) and liquid helium (T=4.2 K). It is found that the cooling of discharge at invariant discharge current and neutral gas density causes a decrease in the interparticle spacing in structures and an increase in the kinetic energy of dust particles. The forming of a superdense dust structure with free boundaries is observed for the first time at 4.2 K. [ABSTRACT FROM AUTHOR]

Nitrate reductase from the haloalkalophilic denitrifying bacterium Halomonas sp. Strain AGJ 1-3 was isolated and purified to homogeneity. The isolated enzyme belongs to a novel family of molybdenum-free nitrate reductases. It presents as a 130–140 kD monomeric protein with specific activity of 250 µmol/min per mg protein. The enzyme reduces not only nitrate, but also other anions, thus showing polyoxoanion reductase activity. Enzyme activity was maximal at pH 7.0 and 70–80°C. [ABSTRACT FROM AUTHOR]

We isolated eight strains of denitrifying bacteria that reduce nitrate and nitrous oxide at pH 10 from Lake Magadi (Kenya). Despite certain differences between the strains, they are similar in terms of G+C content (66.1–68.1 mol %) and DNA–DNA homology (75–92%) and represent different morphotypes of the same species. On the basis of results of partial 16S rRNA sequencing, strain Z-7398-2 was found to be most closely related to the Halomonas campisalis isolate from the Alkali Lake (USA). The DNA–DNA homology level between the tested strain and the type strain of H. campisalis 4A was 88%. These two strains were also similar phenotypically. However, the culture isolated by us was characterized by peculiar properties, such as obligate alkaliphily, which manifested itself in the culture dependence on carbonates and lack of growth at pH values below 7, a nitrous oxide–reducing capacity, and an unusual nitrate reductase that lacked molybdenum and a molybdenum cofactor. [ABSTRACT FROM AUTHOR]

Eight anaerobic enrichment cultures with thiosulfate as electron donor and nitrate as electron acceptor were inoculated with sediment samples from hypersaline alkaline lakes of Wadi Natrun (Egypt) at pH 10; however, only one of the cultures showed stable growth with complete nitrate reduction to dinitrogen gas. The thiosulfate-oxidizing culture subsequently selected after serial dilution developed in two phases. Initially, nitrate was mostly reduced to nitrite, with a coccoid morphotype prevailing in the culture. During the second stage, nitrite was reduced to dinitrogen gas, accompanied by mass development of thin motile rods. Both morphotypes were isolated in pure culture and identified as representatives of the genus Thioalkalivibrio, which includes obligately autotrophic sulfur-oxidizing haloalkaliphilic species. Nitrate-reducing strain ALEN 2 consisted of large nonmotile coccoid cells that accumulated intracellular sulfur. Its anaerobic growth with thiosulfate, sulfide, or polysulfide as electron donor and nitrate as electron acceptor resulted in the formation of nitrite as the major product. The second isolate, strain ALED, was able to grow anaerobically with thiosulfate as electron donor and nitrite or nitrous oxide (but not nitrate) as electron acceptor. Overall, the action of two different sulfur-oxidizing autotrophs resulted in the complete, thiosulfate-dependent denitrification of nitrate under haloalkaliphilic conditions. This process has not yet been demonstrated for any single species of chemolithoautotrophic sulfur-oxidizing haloalkaliphiles. [ABSTRACT FROM AUTHOR]

Equations for the motion of an individual dust grain in the double layer of a negatively charged cylindrical probe in a glow discharge plasma are derived and solved numerically. The distribution of the electric potential near the probe is determined, and the grain charge is calculated as a function of the distance from the probe for different probe potentials. The trajectories of grains with different initial energies are traced. An analysis of the grain trajectories shows that, at a certain distance from the probe, high-energy grains may be recharged; i.e., the grain charge may change sign. The grains are found to have no direct effect on the probe current in a dusty plasma of a glow discharge. © 2001 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Molybdenum- and molybdenum cofactor-free nitrate reductases recently isolated by us from vanadate-reducing bacteria Pseudomonas isachenkovii are likely to mediate vanadate reduction. During anaerobic growth of P. isachenkovii on medium supplemented with nitrate and vanadate, vanadate dissimilation was followed by nitrate consumption, and this process was associated with some structural reorganizations of nitrate reductases. The homogeneous membrane-bound nitrate reductase of P. isachenkovii reduced vanadate with NADH as an electron donor. [ABSTRACT FROM AUTHOR]

A vanadium-binding protein was isolated from the culture medium of the vanadium-reducing bacterium Pseudomonas isachenkovii by utilizing vanadate as the terminal electron acceptor upon anaerobic respiration. The protein was associated with vanadium at a molar ratio of approximately 1:20. It was purified to homogeneity and separated into three components by treatment with 1 M HCl followed by gel filtration: a protein, a vanadium-binding ligand, and inorganic vanadium. Electron paramagnetic resonance analysis showed that vanadium was associated with the protein in the 4+ oxidation state. The distribution of vanadium within the cell was studied by electron microscopy and x-ray microanalysis of P. isachenkovii cells. The results suggest that vanadium, accumulated in special swells on the surface of the cell membranes, is reduced and excreted to the medium. [ABSTRACT FROM AUTHOR]

The scientific and technological revolution has brought to the fore some new and important tasks in the optimization of instruction in the secondary school educational process, a process within which technology is making increasingly broad inroads. [ABSTRACT FROM AUTHOR]

The scientific and technological revolution has brought to the fore some new and important tasks in the optimization of instruction in the secondary school educational process, a process within which technology is making increasingly broad inroads. [ABSTRACT FROM AUTHOR]

Series of mutant genes of prokaryotic uridine phosphorylases (Shewanella oneidensis MR-1, Escherichia coli) were constructed, and the resulting strains-producers of the corresponding proteins were obtained. Proteins were purified, and their physicochemical and fermentative properties were studied. On the basis of the obtained data, the role of individual amino acid residues of the polypeptide chain of uridine phosphorylases in the formation and functioning of the phosphate-binding site in these proteins was shown. The assumption of independent binding of two substrates, ion of inorganic phosphate (Pi) and uridine (Urd), by nucleoside phosphorylases, was made. [ABSTRACT FROM AUTHOR]

The intensity of delayed fluorescence and kinetics processes of eosin molecules in a hanging drop of water solution with ablative silver nanoparticles and without them during phase change have been investigated in this work. Basing on the fluorescence data the obtained times of the initial stage of water-ice phase transitions were amount to 0.04 s and 0.067 s in solutions with and without nanoparticles respectively. It has been established that in the presence of silver nanoparticles in the drop, crystallization process is described by nonlinear low. The femtosecond laser probing technique (λ = 1.03 µm) was used to estimate the thickness of the frozen spherical shell of the drop after 200 ms freezing. At a constant heat removal capacity during cooling, the thickness of the ice shell was 0.1 mm. Numerical modeling of phase transitions in the drop with and without silver nanoparticles was also carried out. The authors solved a boundary value problem of heat conduction for a sphere to obtain the parameters of thermal processes. [ABSTRACT FROM AUTHOR]

A self-consistent nonlocal model of the positive column of a dc glow discharge with dust particles is presented. Radial distributions of plasma parameters and the dust component in an axially homogeneous glow discharge are considered. The model is based on the solution of a nonlocal Boltzmann equation for the electron energy distribution function, drift-diffusion equations for ions, and the Poisson equation for a self-consistent electric field. The radial distribution of dust particle density in a dust cloud was fixed as a given steplike function or was chosen according to an equilibrium Boltzmann distribution. The balance of electron and ion production in argon ionization by an electron impact and their losses on the dust particle surface and on the discharge tube walls is taken into account. The interrelation of discharge plasma and the dust cloud is studied in a self-consistent way, and the radial distributions of the discharge plasma and dust particle parameters are obtained. It is shown that the influence of the dust cloud on the discharge plasma has a nonlocal behavior, e.g., density and charge distributions in the dust cloud substantially depend on the plasma parameters outside the dust cloud. As a result of a self-consistent evolution of plasma parameters to equilibrium steady-state conditions, ionization and recombination rates become equal to each other, electron and ion radial fluxes become equal to zero, and the radial component of electric field is expelled from the dust cloud. [ABSTRACT FROM AUTHOR]

The formation of dusty plasma structures has been experimentally investigated in a cylindrical dc discharge in axial magnetic fields up to 2500 G. The rotation of the dusty plasma structures about the discharge symmetry axis with a frequency depending on the magnetic field has been observed. When the field increases to 700 G, the displacement of dust particles from the axial region of the discharge to the periphery, along with the continuation of the rotation, has been observed. The kinetic temperatures of the dust particles, the diffusion coefficients, and the effective nonideality parameter have been determined for various magnetic fields. The explanation of the features in the behavior of the dust particles in the discharge in the magnetic field has been proposed on the basis of the analysis of ambipolar diffusion in the magnetized plasma. The maximum magnetic field at which the levitation of the dust particles in the discharge is possible has been estimated. [ABSTRACT FROM AUTHOR]

Abstract: A highly active cytochrome c nitrite reductase from the haloalkaliphilic sulfur-oxidizing non-ammonifying bacterium Tv. nitratireducens strain ALEN 2 (TvNiR) was isolated and purified to apparent electrophoretic homogeneity. The enzyme catalyzes reductive conversion of nitrite and hydroxylamine to ammonia without release of any intermediates, as well as reduction of sulfite to sulfide. TvNiR also possesses peroxidase activity. In solution TvNiR exists as a stable hexamer with molecular mass of about 360kDa. Each TvNiR subunit with molecular mass of 64kDa contains, as defined from spectral properties and sequence analysis, eight c-type haems. Seven of them are coordinated by the characteristic CXXCH motifs for haem c binding, while one is bonded by the unique CXXCK motif. So far, this motif coordinating the catalytic haem was found only in bacterial cytochrome c nitrite reductases (ccNiRs). All the residues essential for catalysis in the known ccNiRs were also identified in TvNiR. However, TvNiR is only distantly related to known bacterial ammonifying dissimilatory ccNiRs, sharing no more than 20% homology. [Copyright &y& Elsevier]

Two strains of obligate chemolithoautotrophic sulfur-oxidizing bacteria were isolated from soda-lake sediments by enrichment culture with thiocyanate and nitrate at pH 9.9. The isolates were capable of growth with thiocyanate or thiosulfate as electron donor, either aerobically or anaerobically, and with nitrate or nitrite as electron acceptor. Cyanate was identified as an intermediate of thiocyanate oxidation, while sulfate, ammonia and dinitrogen gas were the final products. The anaerobic growth on thiocyanate plus nitrate was much slower (μmax = 0.006 h-1) than on thiosulfate plus nitrate (μmax = 0.02 h-1), while growth yields were similar (4.8 and 5.1 g protein mol-1, respectively). On the basis of their phenotypic and genetic properties, strains ARhD 1T and ARhD 2 are described as a novel species of the genus Thialkafivibrio, with the highest similarity to Thialkafivibrio denitrificans. The name Thialkafivibrio thiocyanodenitrificans sp. nov. is proposed for this novel species. [ABSTRACT FROM AUTHOR]

Crystals of mutants of uridine phosphorylase from Shewanella oneidensis MR-1 at the active-site threonine residue were obtained, and the three-dimensional structures of the mutants were determined. It was shown that the loop 161–179 responsible for the nucleoside recognition is involved in stabilization of the hexameric structure of the protein and its disorder significantly facilitates the access of nucleoside to the enzyme active site. The role of conformational changes in the enzyme function is discussed. [ABSTRACT FROM AUTHOR]

Generation of supercontinuum (SC) was studied experimentally both in water droplets containing silver nanoparticles (NP) in the temperature range from 2 to 22°C and in droplet ice floes frozen to –15°C. It is established that intensity of SC emission exponentially decays along the droplet diameter following excitation by a train of femtosecond laser pulses and linearly increases with increase in NP concentration. Spectrum of SC emission generated in a water droplet containing NPs is investigated in the presence of localized plasmons producing fluorescence in the vicinity of 430 nm. Propagation of a thermal wave along the diameter (d = 1.0 mm) of a small frozen droplet at a speed of 190 mm/s accompanied by exponentially decaying SC emission is discovered. Mathematical model of heat-transfer processes in an ice floe upon thermal-wave formation is proposed. [ABSTRACT FROM AUTHOR]

Heat transfer in a water drop containing eosine and ablation silver nanoparticles induced by stationary visible laser irradiation, λ = 532 nm, and pulsed IR laser irradiation, λ = 10.6 μm (VIS–IR double laser irradiation), has been studied in the temperature interval of 0.2–50°C. It has been found that the vibratory system of triplet states in a dye molecule heats up after VIS–IR laser irradiation, causing thermoluminescence. The thermoluminescence decay kinetics indicates a new distribution of electron vibration modes in the fluorescence spectrum of dye molecules. If the drop with nanoparticles is small (d < 1 mm), pulsed IR irradiation (τ = 50 ms) gives rise to a thermal front causing thermoluminescence, which travels in the drop with a velocity of 0.85 cm/s. Heat transfer in the drop during the formation of a thermal wave has been simulated. [ABSTRACT FROM AUTHOR]

The characteristics of recombinant phytase from Obesumbacterium proteus have been studied after its integration into Yarrowia lipolytica with a Po1f (pUV3-Op) plasmid. Phytase activity was observed in Y. lipolytica Po1f transformants in a wide pH range (3.5–7.5) and remained at 80% of the initial value after 3-min heating at 95°C, which made it possible to add the enzyme to a fodder produced with heat treatment. In the case of transformant cultivation on low-grade vegetable substrates, they also possessed confirmed phytase activity, as well as an increase in the content of intracellular phosphates as compared to cells of the wild-type Y. lipolytica strain. [ABSTRACT FROM AUTHOR]

We developed an experimental technique of double stationary visible (l = 532 nm) and pulsed infrared (l = 10.6 μm) laser excitation of the electron-vibrational singlet and triplet states of eosin molecules in polyvinyl alcohol. After infrared excitation, delayed fluorescence (τdf ≈ 0.15 s) and thermoluminescence (τТL = 4.7 s) of eosin molecules in polymer matrix occur. The rate constants of these processes depend on the temperature and the presence of water in the polymer. The kinetics of low-temperature processes of thermoluminescence generation and quenching after IR laser pulse is studied. Two characteristic stages of the processes with different activation energies of thermoluminescence are determined: film heating in the 80–270 K temperature range (57.4 J/mol) and ice melting in the polymer matrix within the 270–330 K temperature interval (13.3 kJ/mol). [ABSTRACT FROM AUTHOR]

Abstract: Electronic and vibrational energy transfer processes taking place in molecular complexes in a polymer are investigated under dual-wavelength (visible at λ = 532 nm and IR at wavelength λ = 10.6 μm) laser photoexcitation of eosin molecules (С = 4 × 10-4 М) in air and without it (р ≈ 10-4 Torr) in thin polyvinyl butyral (PVB) films containing silver nanoparticles (R ≈ 36 nm) prepared by laser ablation. Generation of singlet oxygen, singlet-triplet annihilation, and enhancement of plasmon quenching of dye fluorescence are studied. Thermal-energy transfer processes in thin PVB films following pulsed IR excitation are simulated, and the temperature conductivity coefficients of the polymer films in the presence of silver nanoparticles are calculated. Low-temperature processes in PVB films containing dye molecules taking place after IR excitation are investigated, and the mechanism for accelerating intercombination S1 → Т1 transitions as a result of thermal heating and intramolecular vibrational-energy distribution is explained. [ABSTRACT FROM AUTHOR]

Abstract: Bacterial pentaheme cytochrome c nitrite reductases (NrfAs) are key enzymes involved in the terminal step of dissimilatory nitrite reduction of the nitrogen cycle. Their structure and functions are well studied. Recently, a novel octaheme cytochrome c nitrite reductase (TvNiR) has been isolated from the haloalkaliphilic bacterium Thioalkalivibrio nitratireducens. Here we present high-resolution crystal structures of the apoenzyme and its complexes with the substrate (nitrite) and the inhibitor (azide). Both in the crystalline state and in solution, TvNiR exists as a stable hexamer containing 48 hemes—the largest number of hemes accommodated within one protein molecule known to date. The subunit of TvNiR consists of two domains. The N-terminal domain has a unique fold and contains three hemes. The catalytic C-terminal domain hosts the remaining five hemes, their arrangement, including the catalytic heme, being identical to that found in NrfAs. The complete set of eight hemes forms a spatial pattern characteristic of other multiheme proteins, including structurally characterized octaheme cytochromes. The catalytic machinery of TvNiR resembles that of NrfAs. It comprises the lysine residue at the proximal position of the catalytic heme, the catalytic triad of tyrosine, histidine, and arginine at the distal side, channels for the substrate and product transport with a characteristic gradient of electrostatic potential, and, finally, two conserved Ca2+-binding sites. However, TvNiR has a number of special structural features, including a covalent bond between the catalytic tyrosine and the adjacent cysteine and the unusual topography of the product channels that open into the void interior space of the protein hexamer. The role of these characteristic structural features in the catalysis by this enzyme is discussed. [Copyright &y& Elsevier]

A novel cytochrome c nitrite reductase (TvNiR) was isolated from the haloalkalophilic bacterium Thioalkalivibrio nitratireducens. The enzyme catalyses nitrite and hydroxylamine reduction, with ammonia as the only product of both reactions. It consists of 525 amino-acid residues and contains eight haems c. TvNiR crystals were grown by the hanging-drop vapour-diffusion technique. The crystals display cubic symmetry and belong to space group P213, with unit-cell parameter a = 194 Å. A native data set was obtained to 1.5 Å resolution. The structure was solved by the SAD technique using the data collected at the Fe absorption peak wavelength. [ABSTRACT FROM AUTHOR]