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61.
Results of the study on the influence of new antitumor preparations chlofiden and bifolar on sarcoma 45 DNA synthesis and on mitotic activity are given. It was shown that bifolar and chlofiden led to inhibition of label incorporation into DNA (3H-thymidine). Inhibition of mitotic activity after injection of both preparations in toxic doses (DL50) was revealed. During injection of the bifolar functional character of changes was established that is mitotic activity of the preparation during injection was restored. 相似文献
62.
Eremin AN Metelitsa DI Moroz IV Pavlovskaia ZhI Mikhaĭlova RV 《Prikladnaia biokhimiia i mikrobiologiia》2002,38(4):374-380
A comparative kinetic study of extracellular catalases produced by Penicillium piceum F-648 and their variants adapted to H2O2 was performed in culture liquid filtrates. The specific activity of catalase, the maximum rate of catalase-induced H2O2 degradation (Vmax),Vmax/KM ratio, and the catalase inactivation rate constant in the enzymatic reaction (kin, s-1) were estimated in phosphate buffer (pH 7.4) at 30 degrees C. The effective constant representing the rate of catalase thermal inactivation (kin*, s-1) was determined at 45 degrees C. In all samples, the specific activity and KM for catalase were maximum at a protein concentration in culture liquid filtrates of 2.5-3.5 x 10(-4) mg/ml. The effective constants describing the rate of H2O2 degradation (k, s-1) were similar to that observed in the initial culture. These values reflected a twofold decrease in catalase activity in culture liquid filtrates. We hypothesized that culture liquid filtrates contain two isoforms of extracellular catalase characterized by different activities and affinities for H2O2. Catalases from variants 5 and 3 with high and low affinities for H2O2, respectively, had a greater operational stability than the enzyme from the initial culture. The method of adaptive selection for H2O2 can be used to obtain fungal variants producing extracellular catalases with improved properties. 相似文献
63.
MARIE-HÉLÈNE BRÉ JEFFREY DIAMOND ROGER JACQUES 《The Journal of eukaryotic microbiology》1975,22(3):432-434
SYNOPSIS. Deprived of vitamin B12 , Euglena gracilis strain Z ceases to divide which we believe to be a function of the light regime: division inhibition occurs more quickly in continuous light than in alternating (6L : 6D) light and not at all in total darkness. This phenomenon is dependent on the carbon source; cells grown in glutamate-malate medium do not divide regardless of the culture conditions while dl -lactate as carbon source permits growth in darkness in the absence of B12 . Conditions which lead to an increased O2 or decreased CO2 tension in the medium, such as agitation in darkness or incubation in red or white light, result in inhibition of division. This inhibition can be reversed by re-transferring the cells to still culture in the dark or, in the case of light-induced blockage, by the addition of DCMU. 相似文献
64.
STÉPHANE JOUVE MOHAMED IAROCHÈNE BAÂDI BOUYA MBAREK AMAGHZAZ 《Zoological Journal of the Linnean Society》2006,148(4):603-656
A new dyrosaurid is described from the Ypresian of the phosphatic deposits of the Oulad Abdoun Basin of Morocco. It is based on numerous cranial and postcranial remains, allowing an almost complete reconstruction. This new Dyrosaurus species, Dyrosaurus maghribensis sp. nov. , is currently only known from Morocco. It differs from D. phosphaticus , present in contemporaneous levels of Algeria and Tunisia, by several autapomorpies, including a smooth dorsal margin of the parietal and widely opened choanae. A phylogenetic analysis, using 47 taxa and 234 morphological characters, shows the dyrosaurids as the sister taxon of pholidosaurids, which include Elosuchus , Sarcosuchus , Terminonaris and Pholidosaurus , and the thalattosuchians. Goniopholididae is a non-monophyletic group; however, if dyrosaurids are not included in the analysis, the result differs and the goniopholidids form a distinct clade. If Thalattosuchia is excluded, both Goniopholididae and Pholidosauridae become paraphyletic assemblages. Thus, phylogenetic problems remain with respect to longirostrine clade, and more attention should be paid to resolving their evolutionary relationships amongst the crocodyliforms. © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 148 , 603–656. 相似文献
65.
Role of Aromatic Amino-acid Residues in the Binding of Enzymes and Proteins to Nucleic Acids 总被引:2,自引:0,他引:2
CLAUD HÉLÈNE 《Nature: New biology》1971,234(47):120-121
MANY studies have been made of the specificity of interaction between nucleic acids and polypeptides, proteins and enzymes1,2. Electrostatic forces between basic amino-acids and phosphate groups contribute to the stability of the complexes, but selective recognition requires more specific interactions which are not yet understood. The recognition of a specific region of a nucleic acid could be explained if this region has some particular conformation or if there are specific interactions between a few amino-acid residues and the bases of this region. We wish to report results which show that the aromatic amino-acids tryptophan and tyrosine can interact with nucleic acid bases in double stranded nucleic acids. They suggest that aromatic amino-acid residues of enzymes and proteins could participate in the binding to nucleic acids by intercalating between the bases and thus constraining the nucleic acid molecule to adopt a definite position with respect to the protein molecule. 相似文献
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69.
O G Arkhipova V V Iaglov A V Maksimenko L V Pavlovskaia O Iu Konovalova 《Biulleten' eksperimental'no? biologii i meditsiny》1987,103(2):221-223
Dextran-modified hyaluronidase was inhaled or intraperitoneally injected for 4 months to mice with silicosis. Stabilized hyaluronidase was shown to have a marked inhibitory effect on the development of lung fibrosis. Drug inhalation proved to be the most effective. An antifibrotic effect of dextran itself has been observed. 相似文献
70.