Плазменные покрытия, содержащие высокобарные фазы

Results of comparative researches of the initial and processed in a plasma flow oxidic microcomposites, consisting of TiO2, SiO2, Al2O3, ZrO2, and plasma coverings from them – the materials which are characterized by amorphous and crystal structure and strengthened by ultradispersed phases of the stishovit, are presented. It is shown the influence of a type, structure and a way of processing of material (initial powder of different dispersion; the powder obtained in a plasma flow at the different modes and with the normal and accelerated cooling; a plasma layered composite) on the content of silicon oxides, aluminum and titanium, on the type of polymorphic transformations (anatase is found both in powders, and in coverings; the accelerated cooling of spheroids leads to growth of its contents in microcomposites) and also on feature of forming in ceramic materials of a high-bar phase – the stishovit (stishovit it is found only in coverings). It is established that increase in power of the plasma generator leads to increase in extent of amorphicity of plasma-layered composites. In the structure of layered composites three groups of the inclusions, combined by the composition, are revealed: two groups of aluminosilicates and inclusions on the basis of zirconium dioxide. Inclusions of the third group are characterized by two types of structures: homogeneous, consisting of zircon, and plated (with a kernel of dioxide of zirconium and a cover from zircon). The developed layered composites are characterized by high wear resistance, corrosion resistance and antifriction properties. In the conditions of low-temperature plasma at atmospheric pressure the stishovit-containing materials are obtained for the first time.Представлены результаты сравнительных исследований исходных и обработанных в плазменном потоке оксидных микрокомпозитов, состоящих из TiO2, SiO2, Al2O3, ZrO2, и плазменных покрытий из них – материалов, характеризующихся аморфно-кристаллической структурой и упрочненных ультрадисперсными фазами стишовита. Показано влияние вида, состава и способа обработки материала (исходный порошок различной дисперсности; порошок, полученный в плазменном потоке при различных режимах и с обычным и ускоренным охлаждением; плазменный слоевой композит) на содержание оксидов кремния, алюминия и титана; на вид полиморфных превращений (анатаз обнаружен и в порошках, и в покрытиях; ускоренное охлаждение сфероидов приводит к росту его содержания в микрокомпозитах), а также на особенности формирования в керамических материалах высокобарной фазы – стишовита (стишовит обнаружен только в покрытиях). Установлено, что повышение мощности плазменного генератора приводит к увеличению степени аморфизации плазменных слоевых композитов. В структуре слоевых композитов обнаружено три группы включений, объединенных по составу: две группы алюмосиликатов и включений на основе диоксида циркония. Включения третьей группы характеризуются двумя видами структур: однородной, состоящей из циркона, и плакированной (с ядром диоксида циркония и оболочкой из циркона). Разработанные слоевые композиты отличаются высокими износостойкостью, коррозионной стойкостью и антифрикционными свойствами. В условиях низкотемпературной плазмы при атмосферном давлении стишовит-содержащие материалы получены впервые

Purification and characterization of a subtilisin-like proteinases secreted in the stationary growth phase of Bacillus amyloliquefaciens H2

Proteinases secreted during the early and late stationary phases have been isolated from the culture liquid of Bacillus amyloliquefaciens H2 using CM-cellulose ion-exchange chromatography with subsequent FPLC on a Mono S column. Considering the character of hydrolysis of specific chromogenic substrates and the type of inhibition, these enzymes were identified as subtilisin-like proteinases. The molecular weight of both proteinases is 29 kD. The proteolytic activity of the proteinases secreted during the early and late stationary phases towards the synthetic substrate Z-Ala-Ala-Leu-pNA was maximal at pH 8.5 and 9.0, respectively. The maximal activity of both proteinases was observed at 37°C, and the proteins were stable within the pH range of 7.2-9.5. The subtilisin-like proteinases from B. amyloliquefaciens were shown to catalyze synthesis of peptide bonds. © Nauka/Interperiodica 2007

Isolation and characterization of a subtilisin-like proteinase of Bacillus intermedius secreted by the Bacillus subtilis recombinant strain AJ73 at different growth stages

Two subtilisin-like serine proteinases of Bacillus intermedius secreted by the Bacillus subtilis recombinant strain AJ73 (pCS9) on the 28th and 48th h of culture growth (early and late proteinase, respectively) have been isolated by ion-exchange chromatography on CM-cellulose and by FPLC. Molecular weights of both proteinases were determined. The N-terminal sequences of the recombinant protein and mature proteinases of the original strain were compared. Kinetic parameters and substrate specificities of the early and late proteinase were analyzed. Physicochemical properties of the enzymes were studied. © Nauka/Interperiodica 2007

Glutamyl endopeptidase of bacillus intermedius, strain 3-19. purification, properties, cristallization

A homogeneous glutamyl endopeptidase, splitting peptide bonds of glutamic. rarely - of aspartic acid residues in peptides and proteins, was isolated from Bacillus intermedius 319 culture filtrate using chromatography on CM cellulose and Mono S. The enzyme molecular mass =29kDa. pI 8.4. The pro teinase is inhibited by I)FP. The enzyme, like other glutamyl endopeptidasos, reveals two pl[ optima at pH 7.5 and 9.0 for casein and one - at pH 8.0 for Z-Glu-pNA hydrolysis. K =6 mM was found for hydrolysis of the lat ter substrate. Its activity optimum lies at 55(;. The enzyme is stable at ptf 6.5-11.0. Its N-erminal sequence shows 56 per cent coinciding residues. when compared with that of Bacillus licheniformis glutamyl endopeptidase: VVIGDI) GRTKVA'NTRVAPYXXXXITFGGS-. The crystal prismesor plates of the size 0.23-0.3 x 0.15-0.2 x 0.07-0.1 mm have been grown using the vapour diffusion technique in lhe hanging drop followed by macroseeding. The crystals belong to the spat( group B2 with following unit cell parameters: a=69.59 angstrom; b=61.613 angstrom; c=56.107 angst rom; ,- 117.57. The x-ray data set to 1.7 angstrom resolution was collected on the synchrotron (EMBL Gain burg)

Characteristics of a novel secreted zinc-dependent endopeptidase of Bacillus intermedius

A novel zinc-dependent metalloendopeptidase of Bacillus intermedius (MprBi) was purified from the culture medium of a recombinant strain of Bacillus subtilis. The amino acid sequence of the homogeneous protein was determined using MALDI-TOF mass spectrometry. The sequence of the first ten residues from the N-terminus of the mature protein is ASTGSQKVTV. Physicochemical properties of the enzyme and its substrate specificity have been studied. The molecular weight of the metalloproteinase constitutes 19 kDa, the K m and k cat values are 0.06 mM and 1210 sec-1, respectively, and the pI value is 5.4. The effect of different inhibitors and metal ions on the enzyme activity has been studied. Based on the analysis of the amino acid sequence of the active site motif and the Met-turn together with the enzyme characteristics, the novel bacterial metalloproteinase MprBi is identified as a metzincin clan adamalysin/reprolysin-like metalloprotease. © 2010 Pleiades Publishing, Ltd

Optimized medium for the efficient production of bacillus intermedium glutamyl endopeptidase by the recombinant bacillus subtilis

A nutrient medium was elaborated for the efficient production of glutamyl endopeptidase by the recombinant Bacillus subtilis strain AJ73 bearing the Bacillus intermedius 3-19 glutamyl endopeptidase gene within a multicopy plasmid. Optimal concentrations of the main nutrients, peptone and inorganic phosphate, were found using a multifactor approach. To provide for active growth and efficient glutamyl endopeptidase production, the cultivation medium of the recombinant strain should be enriched in phosphorus, organic and inorganic nitrogen sources, and yeast extract. Complex protein substrates, such as casein and gelatin, enhanced the biosynthesis of glutamyl endopeptidase. At the same time, easily metabolizable carbon sources suppressed it. The production of glutamyl endopeptidase was stimulated by the bivalent cations Ca2+, Mg2+, and Co2+

Biosynthesis and localization of glutamylendopeptidase from Bacillus intermedius strain 3-19

The biosynthesis of glutamylendopeptidase from Bacillus intermedius strain 3-19 and localization of the enzyme in the bacterial cells was studied. The synthesis of the enzyme was suppressed by easily metabolizable carbon sources. Inorganic phosphate and NH+ 4 ions stimulated the production of glutamylendopeptidase. Complicated organic substrates such as casein, gelatine, and haemoglobin did not affect the biosynthesis of the enzyme. The divalent metallic ions Ca2+, Mg2+, Co2+ increased the production of glutamylendopeptidase while Zn2+, Cu2+, and Fe2+ reduced the biosynthesis of proteinase. The rate of synthesis of the enzyme increased when the rate of the bacterial growth decreased. The maximum enzyme activity in the culture fluid was determined at the stationary phase of growth. In the cells glutamylendopeptidase was bound to the cytoplasmic membrane, and the maximal enzyme activity was detected in the stationary growth phase. The results facilitated the development of a medium which yielded the maximum glutamylendopeptidase production by B. intermedius strain 3-19

Crystal growth and preliminary X-ray study of glutamic acid specific serine protease from Bacillus intermedius

The glutamic acid specific protease (glutamyl-endopeptidase) from Bacillus intermedius, strain 3-19, was isolated and purified using ion exchange chromatography on CM-cellulose and Mono-S FPLC column. The conditions for crystallization of the enzyme have been discussed. The crystals of enzyme were grown using hanging-drop vapor-diffusion technique. Crystals belong to the space group C2 with unit cell parameters of a = 61.62 Å, b = 55.84 Å, c = 60.40 Å, β = 117.6° X-ray diffraction data to 1.68 Å resolution were collected using synchrotron radiation (EMBL, Hamburg) and an imaging plate scanner. © 1999 Elsevier Science B.V. All rights reserved

Effect of nutrients on the accumulation of glutamyl endopeptidase in the culture liquid of bacillus intermedium 3-19

The effect of nutrients and growth conditions on the accumulation of glutamyl endopeptidase in the culture liquid of Bacillus intermedius 3-19 was studied. Glucose and other readily metabolizable carbon sources were found to suppress the production of the enzyme, while inorganic phosphate and ammonium cations enhanced it. Protein substrates, such as casein, gelatin, and hemoglobin, did not affect enzyme production. Some bivalent cations (Ca2+, Mg2+, Co2+) increased the production of glutamyl endopeptidase, but others (Zn2+, Fe2+, Cu2+) acted in the opposite way. The rate of enzyme accumulation in the culture liquid increased as the growth rate of the bacterium decreased, so that the maximum enzyme activity was observed in the stationary growth phase. Based on the results of this investigation, an optimal medium for the maximum production of glutamyl endopeptidase by B. intermedius 3-19 was elaborated

Effect of nutrients on the accumulation of glutamyl endopeptidase in the culture liquid of Bacillus intermedius 3-19

The effect of nutrients and growth conditions on the accumulation of glutamyl endopeptidase in the culture liquid of Bacillus intermedius 3-19 was studied. Glucose and other readily metabolizable carbon sources were found to suppress the production of the enzyme, whereas inorganic phosphate and ammonium cations enhanced it. Protein substrates, such as casein, gelatin, and hemoglobin, did not affect enzyme production. Some bivalent cations (Ca2+, Mg2+, Co2+) increased the production of glutamyl endopeptidase, but others (Zn2+, Fe2+, Cu2+) acted in the opposite way. The rate of enzyme accumulation in the culture liquid increased as the growth rate of the bacterium decreased, so that the maximum enzyme activity was observed in the stationary growth phase. Based on the results of this investigation, an optimal medium for the maximum production of glutamyl endopeptidase by B. intermedius 3-19 was elaborated. © 2000 MAIK "Nauka/Interperiodica"