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D Sh Burbaev

Publications and source records attributed to D Sh Burbaev.

At least 19 recordsLinked to original sources
PubMed2005

Isolation and Purification of enzymes from ligninolytic complex of the basidial fungus Trametes pubescens (Schumach.) Pilát and study of their properties.

A method for purification of enzymes from the ligninolityc complex of the basidiomycete Trametes pubescens (Schumach.) Pilat has been elaborated. Two homogeneous isoforms of laccases (laccase 1 and laccase 2) as well as a homogeneous preparation of lignin peroxidase were isolated. Basic biochemical parameters of the enzymes were determined, such as the molecular weights (67, 67, and 45 kD, respectively), isoelectric points (5.3, 5.1, and 4.2, respectively), as well as content and composition of the carbohydrate moiety of the laccases (N-acetylglucosamine, mannose, and xylose). The pH dependences and thermal stabilities of the laccases were investigated. The kinetic parameters of the enzymatic reactions catalyzed by the laccases were determined using different substrates, such as catechol, hydroquinone, 2,2 -azinobis-(3-ethylbenzthiazoline-6-sulfonate), and K4Fe(CN)6. The structure of the active sites of both laccases and the lignin peroxidase were studied by EPR, CD, and UV-VIS spectroscopy, as well as using fluorescence analysis. Our studies showed similarity of the spectral characteristics of the two laccases, whereas their kinetic properties were found to be different.

Basidiomycota↗
PubMed1992

The source of non-heme iron that binds nitric oxide in cultivated macrophages.

In cultured macrophages (J 774 line) a decrease in iron-sulfur centers (ISC) was not observed after 5 min treatment with nitric oxide (NO) (10(-7) M NO/10(7) cells). The content of these centers was measured by electron spin resonance (ESR) spectroscopy at 16-60 K. However, the appearance of a characteristic ESR signal at g(av) = 2.03 indicated the formation of dinitrosyl iron complex (DNIC) in these cells. These findings suggest that loosely bound non-heme iron (free iron) but not iron from ISC is mainly involved in DNIC formation. ISC might release iron for DNIC formation after their destruction induced by the products of NO oxidation (NO2, N2O3, etc).

Animals↗
PubMed1991

Several forms of chromaffin granule cytochrome b-561 revealed by EPR spectroscopy.

Low-temperature EPR spectra of chromaffin granule membranes from bovine adrenal medulla reveal 3 different signals of the ferric cytochrome b-561. A typical gZ signal of a low-spin cytochrome observed at g approximately 3 is comprised of a high-potential component with gZ = 3.14 and a low-potential one with gZ = 3.11, the low-potential signal showing significantly faster relaxation. In addition, a highly temperature-sensitive heme signal at g = 3.7 is observed which is fully retained in the preparation of granule membranes with b-561 reduced by 50% but disappears upon full reduction of the cytochrome by ascorbate. The signal is strikingly similar to that of the mitochondrial low-potential cytochrome b heme (bL or b-566). The presence of several forms of b-561 in chromaffin granule membranes may provide a structural basis for the transmembrane electron transfer believe to be catalyzed by this hemoprotein.

Animals↗
PubMed1991

[Iron-sulfur centers in the Staphylococcus aureus respiratory chain].

Using low temperature EPR spectroscopy, signals of iron-sulfur centers with g-factors of 2.02 and 1.94 were detected in the respiratory chain of St. aureus membranes. According to their relaxation parameters and redox properties, these iron-sulfur centers are similar to iron-sulfur centers S-1 and S-3 corresponding to succinate dehydrogenases of mitochondria and bacterial membranes.

Cell Membrane↗
PubMed1983

[Reverse electron transfer in mitochondria of the yeast Endomyces magnusii grown on sucrose].

Some specific features of cytosol-mitochondria interactions during the growth of the Endomyces magnusii yeast on sucrose media were investigated. Under the given experimental conditions exogenous (cytoplasmic) NADH is the main source of reducing equivalents. Using low temperature EPR spectroscopy, it was demonstrated that exogenous NADH can effectively induce reverse electron transfer in the respiratory chain of the yeast. Fluorimetric assays suggest that End. magnusii mitochondria can utilize the reducing equivalents formed by reverse electron transfer for the reductive amination of alpha-ketoglutarate to form glutamate. The intramitochondrial localization of aminotransferases was postulated.

Ascomycota↗
PubMedDate not supplied

[Sulfur ligands within the cluster formations of copper at its strong'binding sites on the cytoplasmic membrane of Escherichia coli].

The analysis of the saturation curves of ESR signals revealed a decrease in the relaxation rate of fast-relaxation Cu(I) complexes on the cytoplasmic membrane of E. coli after the interaction of these bacteria with low concentrations of SH-reagents. It was concluded that the observed changes are associated with the reorganization of Cu clusters due to the binding of SH groups incorporated into the clusters N-ethylmaleimide or Ag(I).

Cell Membrane↗
PubMedDate not supplied

[Changes in the electrical characteristics of the internal surface of cytoplasmic membrane of bacteria Escherichia coli after the binding of microdoses of copper ions by its external surface].

The effect of microdoses of copper ions bound with the external surface of the cytoplasmic membrane of Escherichia coli spheroplasts on the charge density of its superficial structures was investigated by the ESR method. Positively charged spin probes of KAT(n)-type and the newly synthesized KAT15 were used. The experimental data were analyzed using the formalism of Gouy-Chapman theory. The binding of microdoses of copper ions by the external surface of the cytoplasmic membrane changed the value of charge density on the membrane internal surface.

Cell Membrane↗
PubMedDate not supplied

[The source of the iron binding with nitric oxide in activated macrophages].

No decrease in iron-sulphur centers was found in cultured macrophage cells (J774) after the treatment with nitric oxide (10(-7) M NO/10(7) cells) during 5 min. The center content was controlled by the electron spin resonance (ESR) method. The macrophages pretreated with dithionite + methyl viologen showed the formation of dinitrosyl iron complexes (DNIC) with a characteristic ESR signal at g approximately 2.03. The data suggest that loosely bound nonheme iron (free iron) mostly contributes to the formation of these complexes. Iron from iron-containing proteins does not release from these centers under the direct action of nitric oxide. The iron-sulphur centers can be destroyed by the products of nitric oxide oxidation (NO2, N2O3, etc.) as oxidizing and acid agents.

Animals↗
PubMedDate not supplied

[EPR spectra of animal tissues in vitro].

The ESR spectra of animal tissues have been recorded at 13-43 degrees K. The reduction of the ESR signal intensities of the Fe-S proteins have been found in starving mice which is due to the substrate diminishing in these animal tissues.

Animals↗
PubMedDate not supplied

[Formation of a complex between carbon monoxide and cytochrome C].

The conditions of structural modifications of horse heart cytochrome c (pH, salt concentration) have been studied. Under these conditions the rate of carboxycytochrome c formation greatly increases in the course of the reduction process as compared to this rate after cytochrome c reduction and relaxation to the equilibrium state. According to these results the reduced intermediate which appears in the course of reduction has a high affinity for the carbon monoxide. It has been shown that the reduced low-spin cytochrome c practically does not take part in the process of dynamic conformational equilibrium with other cytochrome c forms existing in equilibrium mixture of oxidized and reduced cytochrome c.

Carbon Monoxide↗
PubMedDate not supplied

[Factors influencing formation of dinitrosyl complexes of non-heme iron in vitro preparations of mouse liver and yeasts].

Total content of Fenh and its amounts incorporated into paramagnetic dinitrozyl complexes of Fenh (complexes 2.03) which are formed in vitro in homogenates of mouse liver and yeast preparations treated with nitrogen oxide was determined by means of chemical and ESR methods. Formation of the complexes 2.03 in the liver homogenate is limited by the content of easily dyalized weakly bound Fenh, in yeasts--by the content of pair RS-groups. It is suggested that in the liver preparation Fenh incorporated into the complexes 2.03 is determined by the interaction of reduction cytoplasm agents with ferritin. A change in the content of Fenh may affect the appearance and disappearance of the complexes 2.03 in animal tissues in vivo.

Animals↗
PubMedDate not supplied

[Interaction of ubisemiquinone with the high-potential iron-sulfur center of submitochondrial particle succinate dehydrogenase. EPR study at 240 and 12 degrees K].

The ESR spectra of beef heart submitochondrial particles were measured in the same samples at 240 degrees and 12 degrees K. There is close similarity between the inhibitory action of alpha-thenoyltrifluoroacetone, ethanol and ferricyanide on the non-saturating free radical signal SQ-2 observed at 240 degree K and peak at g=1.99 (and 2.04) which is visible only at very low temperatures. This result strongly supports our previous proposal that both ESR signals are manifestations of the ubisemiquinone complex with the High-Potential Iron-Sulfur protein of succinate dehydrogenase.

Animals↗
PubMedDate not supplied

[Spin glass type structures in chloroplasts].

The nature of discovered in [2] magnetic anisotropy of ESR signal with g approximately 3 appearing in chloroplasts at helium temperatures has been studied and clarified. It was found that a signal with these properties can arise only when dark adapted chloroplasts are cooled down to temperatures lower than 23 K in an external magnetic field (Ho greater than 2.300 Oe). The results obtained indicate that the system studied belongs to the type of "spin glasses", i. e., of the magnetically diluted structures with cooperative magnetic interaction between centres. These cooperative properties can be most distinctly observed at definite temperature and magnetic field strength values.

Chloroplasts↗