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91.
Perić-Mataruga V Prolić Z Nenadović V Mrdaković M Vlahović M 《Electromagnetic biology and medicine》2006,25(3):127-133
The activity of large dorsomedial protocerebral A2' neurosecretory neurons were investigated in late pupae of Tenebrio molitor L, which were exposed to a static magnetic field of 320 mT. Experimental groups were C: the control group which was kept at 5 meters from the magnet; CMF: pupae which were reared in control conditions and sacrificed on the eighth day of pupal stage (parents were kept in a magnetic field); and MF: pupae kept in a permanent magnetic field for eight days. Our results indicate the effects of a static magnetic field on the cytological characteristics and activity of large A2' neurosecretory neurons of Tenebrio molitor pupae. 相似文献
92.
Candida albicans is the most prevalent yeast pathogen in humans, and recently it has become increasingly resistant to the current antifungal agents. In this study we investigated C. albicans dihydroorotate dehydrogenase (DHODH, EC 1.3.99.11), which catalyzes the fourth step of de novo pyrimidine synthesis, as a new target for controlling infection. We propose that the enzyme is a member of the DHODH family 2, which comprises mitochondrially bound enzymes, with quinone as the direct electron acceptor and oxygen as the final electron acceptor. Full-length DHODH and N-terminally truncated DHODH, which lacks the targeting sequence and the transmembrane domain, were subcloned from C. albicans, recombinantly expressed in Escherichia coli, purified, and characterized for their kinetics and substrate specificity. An inhibitor screening with 28 selected compounds was performed. Only the dianisidine derivative, redoxal, and the biphenyl quinoline-carboxylic acid derivative, brequinar sodium, which are known to be potent inhibitors of mammalian DHODH, markedly reduced C. albicans DHODH activity. This study provides a background for the development of antipyrimidines with high efficacy for decreasing in situ pyrimidine nucleotide pools in C. albicans. 相似文献
93.
Krystyna Szczawinska P. A. Ferchmin Richard M. Hann Vesna A. Eterović 《Cellular and molecular neurobiology》1992,12(2):95-106
1. The electric organ of Torpedo nobiliana contained putrescine (PUT), spermidine (SPD), spermine (SPM), and cadaverine (CAD). Traces of acetylated SPD and SPM were occasionaly seen. 2. Upon fractionation of the tissue by differential centrifugation, the polyamines (PA) were found predominantly in the soluble fraction. The postsynaptic membrane fraction, containing a high concentration of acetylcholine receptor (AChR), was proportionally enriched in SPM. The molar ratio of SPM to AChR was approximately two in these membranes. 3. The effect of exogeneous PA on AChR function was studied by two methods: carbamoylcholine (CCh)-dependent 86Rb+ influx into receptor-rich membrane vesicles and [alpha-125I]bungarotoxin (Bgt) binding to the AChR. 4. SPM inhibited both ion influx and the rate of Bgt binding at concentrations above 1 mM, and therefore it appears to act as a competitive antagonist of the AChR. 5. At submicromolar concentrations, and only after preincubation with the receptor-rich membrane, SPM and PUT increased the ion influx by about 20% over control values. 6. Preincubation with 100 nM SPM did not affect the equilibrium binding of iodinated toxin or the rate of toxin binding, and therefore SPM was not uncovering new receptors. 7. By measuring the initial rate of toxin binding after different periods of preincubation with 1 microM CCh, the rate of the slow phase of receptor desensitization was determined. This rate was not changed by 100 nM SPM. 8. Although these results suggest that at low concentrations SPM is a positive modulator of the AChR, the precise mechanism of action is not determined yet. 相似文献
94.
Ines Batinić-Haberle Salvatore Cuzzocrea Júlio S. Rebouças Gerardo Ferrer-Sueta Emanuela Mazzon Rosanna Di Paola Rafael Radi Ivan Spasojević Ludmil Benov Daniela Salvemini 《Free radical biology & medicine》2009,46(2):192-201
MnTBAP is often referred to as an SOD mimic in numerous models of oxidative stress. We have recently reported that pure MnTBAP does not dismute superoxide, but commercial or poorly purified samples are able to perform O2·?dismutation with low-to-moderate efficacy via non-innocent Mn-containing impurities. Herein, we show that neither commercial nor pure MnTBAP could substitute for SOD enzyme in a SOD-deficient Escherichia coli model, whereas MnTE-2-PyP-treated SOD-deficient E. coli grew as well as a wild-type strain. This SOD-specific system indicates that MnTBAP does not act as an SOD mimic in vivo. In another model, carrageenan-induced pleurisy in mice, inflammation was evidenced by increased pleural fluid exudate and neutrophil infiltration and activation: these events were blocked by 0.3 mg/kg MnTE-2-PyP and, to a slightly lesser extent, by 10 mg/kg of either MnTBAP. Also, 3-nitrotyrosine formation, an indication of peroxynitrite existence in vivo, was blocked by both compounds; again MnTE-2-PyP was 33-fold more effective. Pleurisy model data indicate that MnTBAP exerts some protective actions in common with MnTE-2-PyP, which are not O2·? related and can be fully rationalized if one considers that the common biological role shared by MnTBAP and MnTE-2-PyP is related to their reduction of peroxynitrite and carbonate radical, the latter arising from ONOOCO2 adduct. The log kcat (O2·?) value for MnTBAP is estimated to be about 3.16, which is ~ 5 and ~ 6 orders of magnitude smaller than the SOD activities of the potent SOD mimic MnTE-2-PyP and Cu,Zn-SOD, respectively. This very low value indicates that MnTBAP is too inefficient at dismuting superoxide to be of any biological impact, which was confirmed in the SOD-deficient E. coli model. The peroxynitrite scavenging ability of MnTBAP, however, is only ~ 2.5 orders of magnitude smaller than that of MnTE-2-PyP and is not significantly affected by the presence of the SOD-active impurities in the commercial MnTBAP sample (log kred (ONOO?) = 5.06 for pure and 4.97 for commercial sample). The reduction of carbonate radical is equally fast with MnTBAP and MnTE-2-PyP. The dose of MnTBAP required to yield oxidative stress protection and block nitrotyrosine formation in the pleurisy model is > 1.5 orders of magnitude higher than that of MnTE-2-PyP, which could be related to the lower ability of MnTBAP to scavenge peroxynitrite. The slightly better protection observed with the commercial MnTBAP sample (relative to the pure MnTBAP) could arise from its impurities, which, by scavenging O2·?, reduce consequently the overall peroxynitrite and secondary ROS/RNS levels. These observations have profound biological repercussions as they may suggest that the effect of MnTBAP observed in numerous studies may conceivably relate to peroxynitrite scavenging. Moreover, provided that pure MnTBAP is unable to dismute superoxide at any significant extent, but is able to partially scavenge peroxynitrite and carbonate radical, this compound may prove valuable in distinguishing ONOO?/CO3·? from O2·? pathways. 相似文献
95.
96.
Philippe Fuchs Nils Rugen Chris Carrie Marlene Elssser Iris Finkemeier Jonas Giese Tatjana M. Hildebrandt Kristina Kühn Veronica G. Maurino Cristina Ruberti Mareike Schallenberg‐Rüdinger Janina Steinbeck Hans‐Peter Braun Holger Eubel Etienne H. Meyer Stefanie J. Müller‐Schüssele Markus Schwarzlnder 《The Plant journal : for cell and molecular biology》2020,101(2):420-441
97.
Saša N. Malkov Miodrag V. Živković Miloš V. Beljanski Srđan Đ. Stojanović Snežana D. Zarić 《The protein journal》2009,28(2):74-86
Using the data from Protein Data Bank the correlations of primary and secondary structures of proteins were analyzed. The
correlation values of the amino acids and the eight secondary structure types were calculated, where the position of the amino
acid and the position in sequence with the particular secondary structure differ at most 25. The diagrams describing these
results indicate that correlations are significant at distances between −9 and 10. The results show that the substituents
on Cβ or Cγ atoms of amino acid play major role in their preference for particular secondary structure at the same position
in the sequence, while the polarity of amino acid has significant influence on α-helices and strands at some distance in the
sequence. The diagrams corresponding to polar amino acids are noticeably asymmetric. The diagrams point out the exchangeability
of residues in the proteins; the amino acids with similar diagrams have similar local folding requirements.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
98.
Niko Radulović Milan Dekić Zorica Stojanović-Radić Radosav Palić 《Central European Journal of Biology》2009,4(3):404-410
Essential oils from Erodium cicutarium were obtained by hydrodistillation (samples consisting of entire plants (ec1), leaves and stems (ec2)) and analyzed by gas
chromatography (GC) and gas chromatography-mass spectrometry (GC/MS), resulting in a total of 177 components being identified.
The essential oils were of a very similar chemical composition and consisted mainly of aliphatic compounds and their derivatives.
Fatty acids and fatty acid derived compounds were the most common, 51.3% (ec1) and 60.1% (ec2), followed by carotenoid derived
compounds, 12.6% (ec1) and 20.2% (ec2), and then terpenoids, 14.9% (ec1) and 14.2% (ec2). The main constituents in the oils
were hexadecanoic acid, 22.8% (ec2) and 35.9% (ec1) and hexahydrofarnesyl acetone, 10.8% (ec2) and 11.6% (ec1). The results
obtained differ markedly from those previously reported for the same species. 相似文献
99.
100.
Christa Schleper Richard Röder Tatjana Singer Wolfram Zillig 《Molecular genetics and genomics : MGG》1994,243(1):91-96
Three phenotypically stable mutants of the extremely thermophilic archaeon Sulfolobus solfataricus have been isolated by screening for β-galactosidase negative colonies on plates with X-Gal (5-bromo-4-chloro-3-indolyl-(3-d-galactopyranoside). From one of these mutants an insertion element, designated ISC1217, was isolated and characterized. Sequence analysis of ISC1217 and of the regions adjacent to the insertion site in the β-galactosidase gene revealed features typical of a transposable element: ISC1217 contained terminal inverted repeats and was flanked by a direct repeat of 6 bp. The 1147 by sequence contained an open reading frame encoding a putative protein of 354 amino acid residues and, overlapping this, two smaller open reading frames on the opposite strand. There were approximately 8 copies of the insertion element in the S. solfataricus genome. ISC1217 did not cross-hybridize with DNA of other Sulfolobus species. All three independently isolated β-galactosidase mutants of S. solfataricus arose by transposition of ISC1217 or a related element. 相似文献