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排序方式: 共有431条查询结果,搜索用时 218 毫秒
1.
V. N. Barai A. I. Zinchenko L. M. Zalashko L. A. Eroshevskaya I. A. Mikhailopulo 《Biotechnology letters》1995,17(6):599-602
Summary The title compound was prepared by a three-stage enzymatic procedure consisting of (i) RNA hydrolysis to a mixture of ribonucleosides using intact mycelium of Spicaria violacea, (ii) transribosylation of exogenous adenine employing whole cells of Escherichia coli as a biocatalyst, and (iii) conversion of formed adenosine into ATP by the enzymes of alcohol fermentation and the kinases extracted from baker's yeast. 相似文献
2.
S A Novgorodov V G Gogvadze B I Medvedev V P Zinchenko 《Biokhimii?a (Moscow, Russia)》1987,52(6):943-948
Accumulation of Ca2+ by rat liver mitochondria in the presence of inorganic phosphate results in spontaneous activation of respiration accompanied by a progressive loss of the accumulated cation. The lipid peroxidation inhibitor, ionol, completely prevents and reverses the Ca2+/phosphate-induced loss of accumulated Ca2+ and restores the respiration to state 4 level without having any effect on the rate of Ca2+ accumulation and respiration in the presence of an uncoupler. No correlation between the ionol-dependent loss of Ca2+ and the formation of malonic dialdehyde in mitochondria was found. The measurements of delta psi across the inner mitochondrial membrane during a progressive loss of Ca2+ suggest that the Ca2+/phosphate-induced "uncoupling" is mainly due to the appearance of electrogenic fluxes (but not Ca2+ cycling) which is under control of some products of initial steps of lipid peroxidation. 相似文献
3.
A S Taisova N P Korolev N S Griaznova E Ia Zinchenko Z I Lesovaia 《Antibiotiki i khimioterapii͡a》1989,34(7):496-504
Interaction between penicillins and model membrane systems, flat black bilayer lipid membranes (BLM) composed of vegetable or bacterial phospholipids was studied with an account of the complicated structure of bacterial cell membranes and possible presence in them of "pure" bilayer lipid areas. By their effect on electroconductivity of the BLM the antibiotics could be divided into three groups: those having no effect on the BLM electroconductivity at the maximum concentrations i.e. benzylpenicillin, carbenicillin, piperacillin (at pH 6.0 and 7.0) and ampicillin (at pH 6.0), those insignificantly changing electroconductivity of the BLM i.e. carfecillin and azlocillin and those having a significant effect on the BLM electroconductivity i.e. ampicillin N-acyl derivatives and 6-APA. The effect of ampicillin on the BLM conductivity markedly depended on the electrolite pH. The penicillins bound to the bilayer and induced changes in the transmembrane potential (evident from the changes in the second harmonic of the capacitive current) and the BLM elasticity-capacitance parameters (evident from the changes in the ratio of the amplitudes of the first and third harmonics). It was shown that all the penicillins penetrated through the BLM composed of either vegetable or bacterial phospholipids. The capacity for the transmembrane transfer without changing of the bilayer conductivity must be connected with the fact that the penetrating antibiotics did not induce any changes in the BLM structure. The effect on the conductivity probably depended in its turn on the form of the molecule and the ratio of the hydrophilic and hydrophobic parts in it. 相似文献
4.
We have isolated the delta-globin gene of the New-World spider monkey,
Ateles geoffroyi, and compared its nucleotide sequence with those of other
primate delta- and beta-globin genes. Among primate delta-globin genes, the
rate of nonsynonymous substitutions is much less than the rate of
synonymous substitutions. This suggests that primate delta- globin genes
may remain under evolutionary conservation, perhaps because hemoglobin A2
has an as yet unknown physiological importance.
相似文献
5.
A. I. Zinchenko V. N. Barai S. B. Bokut N. V. Dudchik E. I. Kvasyuk I. A. Mikhailopulo 《Biotechnology letters》1991,13(2):87-90
Summary The title compound was prepared by a two step enzymatic procedure consisting of DNA hydrolysis to the mixture of 2-deoxynucleosides followed by a transdeoxyribosilation of exogenous adenine. 相似文献
6.
The effect of spermine (50-400 microM) on the Ca-transporting system of brain mitochondria was studied. In a medium containing Mg2+ and ATP, spermine facilitates the accumulation of Ca2+ by decreasing Km of the uniporter. Spermine inhibits Na-stimulated Ca2+ efflux; this effect is dependent on the ionic strength of the medium--it is decreased when KCl concentration is increased from 20 to 120 mM. Spermine (200 microM) decreases (by 50%) the steady state concentration of Ca2+ maintained by mitochondria. The importance of spermine as a regulator of Ca2+-transport in brain mitochondria is discussed. 相似文献
7.
A S Gukovskaya V P Zinchenko V V Petrunyaka B I Khodorov Y V Evtodienko 《European journal of biochemistry》1986,161(1):249-256
The regulation of free Ca2+ concentration by intracellular pools and their participation in the mitogen-induced changes of the cytosolic free Ca2+ concentration, [Ca2+]i, was studied in digitonin-permeabilized and intact rat thymocytes using a Ca2+-selective electrode, chlortetracycline fluorescence and the Ca2+ indicator quin-2. It is shown that in permeabilized thymocytes Ca2+ can be accumulated by two intracellular compartments, mitochondrial and non-mitochondrial. Ca2+ uptake by the non-mitochondrial compartment, presumably the endoplasmic reticulum, is observed only in the presence of MgATP, is increased by oxalate and inhibited by vanadate. The mitochondria do not accumulate calcium at a free Ca2+ concentration below 1 microM. The non-mitochondrial compartment has a greater affinity for calcium and is capable of sequestering Ca2+ at a free Ca2+ concentration less than 1 microM. At free Ca2+ concentration close to the cytoplasmic (0.1 microM) the main calcium pool in permeabilized thymocytes is localized in the non-mitochondrial compartment. Ca2+ accumulated in the non-mitochondrial pool can be released by inositol 1,4,5-triphosphate (IP3) which has been inferred to mediate Ca2+ mobilization in a number of cell types. Under experimental conditions in which ATP-dependent Ca2+ influx is blocked, the addition of IP3 results in a large Ca2+ release from the non-mitochondrial pool; thus IP3 acts by activation of a specific efflux pathway rather than by inhibiting Ca2+ influx. SH reagents do not prevent IP3-induced Ca2+ mobilization. Addition of the mitochondrial uncouplers, FCCP or ClCCP, to intact thymocytes results in no increase in [Ca2+]i measured with quin-2 tetraoxymethyl ester whereas the Ca2+ ionophore A23187 induces a Ca2+ release from the non-mitochondrial store(s). Thus, the data obtained on intact cells agree with those obtained in permeabilized thymocytes. The mitogen concanavalin A increases [Ca2+]i in intact thymocytes suspended in both Ca2+-containing an Ca2+-free medium. This indicates a mitogen-induced mobilization of an intracellular Ca2+ pool, probably via the IP3 pathway. 相似文献
8.
The existence of Ca2+-dependent K+ channels in rat thymocytes, their activation by Ca2+-ionophore A23187 and concanavalin A, and inhibition by EGTA and quinine have been demonstrated using K+-electrode and fluorescent potential probe diS-C3-(5). The results indicate that Ca2+-dependent K+ channels take part in the increase of potassium permeability, one of the early events in mitogenic stimulation of lymphocytes. 相似文献
9.
Biochemical pathways in prokaryotes can be traced backward through evolutionary time 总被引:10,自引:0,他引:10
For the first time, a credible prokaryotic phylogenetic tree is being
assembled by Woese and others using quantitative sequence analysis of
oligonucleotides in the highly conservative rRNA. This provides an
evolutionary scale against which the evolutionary steps that led to the
arrangement and regulation of contemporary biochemical pathways can be
measured. This paper presents an emerging evolutionary picture of aromatic
amino acid biosynthesis within a large superfamily assemblage of
prokaryotes that is sufficiently developed to illustrate a new perspective
that will be applicable to many other biochemical pathways.
相似文献
10.
A S Gukovskaya E S Trepakova V P Zinchenko Y N Korystov V V Bezuglov 《Biochimica et biophysica acta》1992,1111(1):65-74
The sulfhydryl reagent thimerosal at concentrations 5-100 microM has been found to induce a variety of changes in ion transport in rat thymocytes. In particular, [Ca2+]i increases about 10-fold from the basal level. The [Ca2+]i response to thimerosal displays a two-stage time course, with the main [Ca2+]i rise during the second stage. Evidence has been obtained for the depletion of intracellular Ca2+ pools in thimerosal-treated cells, however, Ca2+ mobilization from intracellular stores does not contribute significantly into [Ca2+]i rise. Thimerosal elicits permeability not only for Ca2+, but also for Mn2+ and Ni2+, which is Ca(2+)-dependent. We failed to get any evidence on thimerosal-induced inhibition of the plasma membrane Ca(2+)-ATPase. The induction of Ca2+ influx, rather than inhibition of Ca(2+)-ATPase, accounts for the disturbance of [Ca2+]i homeostasis in thimerosal-treated cells. Thimerosal also elicits changes in monovalent ion fluxes resulting in marked depolarization. The latter seems unrelated to the changes in [Ca2+]i and is suggested to be mediated both by increased permeability for Na+ and a decreased one for K+. Thimerosal significantly stimulates AA release from thymocytes. Evidence has been presented that AA metabolite(s), probably, LO product(s), may mediate the changes in the transport of mono- and divalent cations elicited by the sulfhydryl reagent. Prolonged treatment of thymocytes with thimerosal resulted in cell death. 相似文献