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1.
The temperature stability of the cytoplasmic enzyme of the glycolysis of lactate dehydrogenase from a pig muscle (isoenzyme M4) in a complex with the anion polyelectrolyte poly(styrenesulfonate) has been investigated by the methods of adiabatic differential scanning microcalorimetry, the own protein fluorescence, and circular dichroism. Calorimetric investigations of complex of lactate dehydrogenase with poly(styrenesulphonate) in 50 mM phosphate buffer at pH 7.0 have shown that the temperature of the transition and enthalpy of lactate dehydrogenase thermal denaturation sharply decreases with growing weight ratio poly(styrenesulphonate)/lactate dehydrogenase, though at 20 degrees C the enzyme activity of lactate dehydrogenase remains unchanged for several hours irrespective of the addition of poly(styrenesulphonate). The addition of phosphate ions to the solution enhances the resistance of lactate dehydrogenase to both thermal denaturation and inactivation by polyelectrolyte. The data obtained are interpreted from the viewpoint of a special role of two anion-binding centers in intersubunits contacts of lactate dehydrogenase, which enhance its resistance to both thermal denaturation and destruction by polyelectrolyte. 相似文献
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E.?V.?SpirinaEmail author E.?V.?Durdenko N.?E.?Demidov A.?A.?Abramov V.?E.?Romanovsky E.?M.?Rivkina 《Paleontological Journal》2017,51(13):1440-1452
Cryopegs, lenses of hypersaline unfrozen soil or water within permafrost, are a model for astrobiology, since free water can only be present on cryogenic bodies and planets in the form of brine. In this paper the diversity of aerobic halophilic-psychrotrophic microorganisms from an Alaskan cryopeg (Barrow Cape) were studied and described for the first time. This cryopeg is characterized by a constant subzero temperature (–7°C), high salinity (total mineralization is about 120 g/L) and isolation from external influences for a geologically significant period of time. Our study has revealed a large number of microorganisms capable of growth at low temperature (4°C) in a wide range of salinities from 5 to 250 g/L of NaCl, the latter being 3 times higher than the natural salt concentration of the Alaskan cryopeg. The microorganisms identified are comprised of four major phyla: Actinobacteria (genera Brevibacterium, Citricoccus, Microbacterium), Firmicutes (genus Paenibacillus), Bacteroidetes (genus Sphingobacterium), and Proteobacteria (genus Ochrobactrum). 相似文献
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E. V. Durdenko S. M. Kuznetsova L. V. Basova S. A. Tikhonenko E. A. Saburova 《Biophysics》2011,56(4):618-627
The functional state of three proteins of different molecular weight (urease, lactate dehydrogenase, and hemoglobin) in the
presence of the linear polyelectrolytes poly(allylamine hydrochloride) (PAA) and sodium poly(styrenesulfonate) (PSS) in the
dissolved state and of the same polyelectrolytes bound to the surface of microspheres has been investigated. Microspheres
were prepared by consecutive absorption of oppositely charged polyelectrolytes so that the outer layer of the shell was PAA
for the acidic protein urease, and PSS for the alkaline proteins LDH and hemoglobin. It was shown that the dissolved polyelectrolyte
completely inactivates all three proteins within one minute with a slight difference in the time constant. (By Hb inactivation
are conventionally meant changes in the heme environment observed from the spectrum in the Soret band.) In the presence of
microspheres, the proteins were adsorbed on their surface; in this case, more than 95% of the activity was retained within
two hours. The proportion of the protein adsorbed on microspheres accounted for about 98% for urease, 72% for Hb, and 35%
for LDH, as determined from the tryptophan fluorescence data. The interaction of hemoglobin with another type of charged colloidal
particles, phospholipid vesicles, leads to the destruction of the tertiary structure of the protein, which made itself evident
in the optical absorption spectra in the Soret band, as well as the spectra of tryptophan fluorescence and circular dichroism.
In this case, according to circular dichroism, the percentage of α-helical structure of Hb was maintained. The differences
in the physical and chemical mechanisms of interaction of proteins with these two types of charged colloidal particles that
leads to differences in the degree of denaturing effects are discussed. 相似文献
4.
It has been shown by X-ray structure analysis that proteins have specific anion-binding sites for sulfate, citrate, and phosphate ions; however, the functional role of these anions is not always clear. Thus, it is unknown which of two phosphate anions, mono- or divalent, determines the stability of cellular proteins under stress conditions. In the present work, the influence of phosphate, sulfate, and chloride on the stability of lactate dehydrogenase (LDH) in the presence of poly(styrenesulfonate) (PSS) has been investigated by the methods of steady-state kinetics and intrinsic protein fluorescence. The study is based on the analysis of differences between the influence of phosphate and sulfate ions on the process at two pH values, 6.2 and 7.0, at which the ratio of the concentrations of mono- and bivalent phosphate forms differs, whereas sulfate remains in the bivalent form. It was shown that the differences between the influence of phosphate and sulfate ions at pH 7.0 were greater; divalent phosphate ions much more effectively stabilized LDH against destruction by a polyelectrolyte compared with sulfate and monovalent phosphate. It was concluded that, of two anion-binding sites of the LDH molecule, the intersubunit center plays the most important role in its stabilization against destruction by polyelectrolyte, and, of two forms of phosphate anions, its bivalent form HPO 4 ?2 plays the stabilizing role. 相似文献
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DAVID G. GARBUZ OLGA G. ZATSEPINA ANDREY A. PRZHIBORO IRINA YUSHENOVA IRINA V. GUZHOVA MICHAEL B. EVGEN’EV 《Molecular ecology》2008,17(21):4763-4777
A population of Stratiomys japonica, a species belonging to the family Stratiomyidae (Diptera), common name ‘soldier flies’, occurs in a hot volcanic spring, which is apparently among the most inhospitable environments for animals because of chemical and thermal conditions. Larvae of this species, which naturally often experience temperatures more than 40 °C, have constitutively high concentrations of the normally inducible heat-shock protein Hsp70, but very low level of corresponding mRNA. Larvae of three other species of the same family, Stratiomys singularior, Nemotelus bipunctatus and Oxycera pardalina, are confined to different type semi-aquatic habitats with contrasting thermal regime. However, all of them shared the same pattern of Hsp70 expression. Interestingly, heat-shock treatment of S. japonica larvae activates heat-shock factor and significantly induces Hsp70 synthesis, whereas larvae of O. pardalina, a species from constant cold environment, produce significantly less Hsp70 in response to heat shock. Adults of the four species also exhibit lower, but detectable levels of Hsp70 without heat shock. Larvae of all species studied have very high tolerance to temperature stress in comparison with other Diptera species investigated, probably representing an inherent adaptive feature of all Stratiomyidae enabling successful colonization of highly variable and extreme habitats. 相似文献
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The phylogeny of selected genera from four subfamilies of fungus gnats (Diptera: Mycetophilidae) – Manotinae, Leiinae, Sciophilinae and Gnoristinae (including Metanepsiini) – is reconstructed based on the combined analysis of five mitochondrial (12S, 16S, COI, COII, cytB) and two nuclear (28S, ITS2) gene markers. Results of the different analyses all support Manotinae as a monophyletic group, with Leiinae as the sister group. Allactoneura DeMeijere is nested in the monophyletic and strongly supported clade of Leiinae. The tribe Metanepsiini is revealed as paraphyletic and the genera Metanepsia Edwards and Chalastonepsia Søli do not appear to be closely related. The genera Docosia Winnertz, Ectrepesthoneura Enderlein, Novakia Strobl and Syntemna Winnertz were placed with a group of genera included traditionally in the Gnoristinae. The monophyly of Dziedzickia Johannsen and Phthinia Winnertz is not supported. The genera of Sciophilinae (excluding Paratinia Mik but including Eudicrana Loew) form a monophyletic group in the Bayesian model. 相似文献
10.
E. V. Durdenko S. M. Kuznetsova S. A. Tikhonenko V. I. Emelyanenko E. A. Saburova 《Biophysics》2010,55(4):535-543
The temperature stability of the cytoplasmic enzyme of glycolysis, lactate dehydrogenase from pig muscle (isoenzyme M4) in
complex with anionic polyelectrolyte poly(styrenesulfonate) has been investigated by the methods of adiabatic differential
scanning microcalorimetry, own protein fluorescence, and circular dichroism. Calorimetric investigations of the complex of
lactate dehydrogenase with poly(styrenesulfonate) in 50 mM phosphate buffer at pH 7.0 have shown that the temperature of the
transition and enthalpy of lactate dehydrogenase thermal denaturation sharply decreases with growing weight ratio poly(styrenesulfonate)/lactate
dehydrogenase, though at 20°C the enzyme activity of lactate dehydrogenase remains unchanged for several hours irrespective
of the addition of poly(styrenesulfonate). The addition of phosphate ions to the solution enhances the resistance of lactate
dehydrogenase to both thermal denaturation and inactivation by polyelectrolyte. The data obtained are interpreted from the
viewpoint of a special role of two anion-binding centers in intersubunits contacts of lactate dehydrogenase, which enhance
its resistance to both thermal denaturation and destruction by polyelectrolyte. 相似文献