共查询到20条相似文献,搜索用时 15 毫秒
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Karakawa T Sato K Muramoto Y Mitani Y Kitamado M Iwanaga T Nabeshima T Maruyama K Nakagawa K Ishida K Sasamoto K 《Biochemical and biophysical research communications》2008,370(1):93-97
Electron spin resonance using spin-trapping is a useful technique for detecting direct reactive oxygen species, such as superoxide (). However, the widely used spin trap 2,2-dimethyl-3,4-dihydro-2H-pyrrole N-oxide (DMPO) has several fundamental limitations in terms of half-life and stability. Recently, the new spin trap 2-diphenylphosphinoyl-2-methyl-3,4-dihydro-2H-pyrrole N-oxide (DPhPMPO) was developed by us. We evaluated the biological applicability of DPhPMPO to analyze in both cell-free and cellular systems. DPhPMPO had a larger rate constant for and formed more stable spin adducts for than DMPO in the xanthine/xanthine oxidase (X/XO) system. In the phorbol myristate acetate-activated neutrophil system, the detection potential of DPhPMPO for was significantly higher than that of DMPO (kDMPO = 13.95 M−1 s−1, kDPhPMPO = 42.4 M−1 s−1). These results indicated that DPhPMPO is a potentially good candidate for trapping in a biological system. 相似文献
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Mihoko Kondo-Nakamura Koichi Uemura Ken-ichi Yoshida 《Biochemical and biophysical research communications》2010,393(3):449-163
We examined whether and how pretreatment with carbon monoxide (CO) prevents apoptosis of cardioblastic H9c2 cells in ischemia-reperfusion. Reperfusion (6 h) following brief ischemia (10 min) induced cytochrome c release, activation of caspase-9 and caspase-3, and apoptotic nuclear condensation. Brief CO pretreatment (10 min) or a caspase-9 inhibitor (Z-LEHD-FMK) attenuated these apoptotic changes. Ischemia-reperfusion increased phosphorylation of Akt at Ser472/473/474, and this was enhanced by CO pretreatment. A specific Akt inhibitor (API-2) blunted the anti-apoptotic effects of CO in reperfusion. In normoxic cells, CO enhanced generation, which was inhibited by a mitochondrial complex III inhibitor (antimycin A) but not by a NADH oxidase inhibitor (apocynin). The CO-enhanced Akt phosphorylation was suppressed by an scavenger (Tiron), catalase or a superoxide dismutase (SOD) inhibitor (DETC). These results suggest that CO pretreatment induces mitochondrial generation of , which is then converted by SOD to H2O2, and subsequent Akt activation by H2O2 attenuates apoptosis in ischemia-reperfusion. 相似文献
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Carlson BA Lee BJ Hatfield DL 《Biochemical and biophysical research communications》2008,375(1):86-90
We used Xenopus oocytes as an intracellular system to study ribosomal frameshifting. Microinjection of oocytes with a construct encoding the naturally occurring UUU or AAC codon at the frameshift site demonstrated that the level of frameshifting was similar or lower than found normally in retroviral frameshifting in mammalian cells, suggesting that oocytes are a reliable system to study this event. Phenylalanine (Phe) or asparagine (Asn) tRNAs with and without the highly modified wyebutoxine (Y) or queuosine (Q) base, respectively, were microinjected to assess their ability to promote frameshifting. inhibited the level of frameshifting, while promoted frameshifting providing evidence that the hypomodified form does not act only to enhance frameshifting, but is an essential requirement. Both and were used indiscriminately in frameshifting, whether the frameshift site contained the wild-type AAC, or the mutant AAU codon, suggesting that Q base modification status does not influence this process. 相似文献
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Takuyo Aita 《Bio Systems》2010,101(3):194-199
In this paper, we consider two complementary cost functions for the landscape exploring processes to obtain the global optimum sequence through in vitro evolution protocol: one is the entropic cost Cetp, which is based on the deviation from the uniformity of a mutant distribution in sequence space, and the other is the energetic cost Ceng, which is based on the total number of sequences to be generated and evaluated. Based on a prior knowledge about the structure of a given fitness landscapes, the conductor of the experiment can think up the efficient search algorithm (ESA), which requires the minimum number of points (=sequences) to be searched up to the global optimum. For five typical fitness landscapes, we considered their respective (putative) ESA, and based on the ESA. As a result, we found a trade-off relationship between and for every case, that is, is approximately equal to the logarithm of the volume of the sequence space. and are interpreted in terms of the information-theoretic concepts. 相似文献
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Subrata Patra 《Inorganica chimica acta》2010,363(8):1639-135
Metalloreceptors containing ruthenium(II) bipyridine unit as fluorophore and pendant macrocyclic units as ionophore have been synthesized and their luminescence and electrochemical properties have been investigated. Ion-binding study of these fluoroionophore with the anions F−, Cl−, Br−, I−, , , , , CH3COO−, and and cations Na+, K+, Mg2+, Ca2+, Zn2+, Ba2+, Sr2+ Cd2+, Hg2+, Pb2+ and Cu2+, monitored by luminescence and 1H NMR spectral changes, reveal strong interactions of and F− for 2 and 3 and of Cu2+ only for 3. Luminescence titrations for 2 and 3 have been carried out to determine binding constants (Ks), and the calculated values are in the range 2.85 × 102 to 4.48 × 104 M−1. The 1H NMR spectral changes for 2 and 3 with the addition of increasing concentration of F− and exhibit substantial low-field shift of the CONH proton indicating its involvement in complex formation with the anions. The adduct of 2 and 3 have been isolated and characterized by 1H and 31P NMR, mass and IR spectroscopy. The results are discussed in light of selectivity, structures of the anion bound complexes and their luminescence property. 相似文献
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Mitani Y Sato K Muramoto Y Karakawa T Kitamado M Iwanaga T Nabeshima T Maruyama K Nakagawa K Ishida K Sasamoto K 《Biochemical and biophysical research communications》2008,372(1):19-23
Pirfenidone (PFD) is focused on a new anti-fibrotic drug, which can minimize lung fibrosis etc. We evaluated the superoxide () scavenging activities of PFD and the PFD-iron complex by electron spin resonance (ESR) spectroscopy, luminol-dependent chemiluminescence assay, and cytochrome c reduction assay. Firstly, we confirmed that the PFD-iron complex was formed by mixing iron chloride with threefold molar PFD, and the complex was stable in distillated water and ethanol. Secondary, the PFD-iron complex reduced the amount of produced by xanthine oxidase/hypoxanthine without inhibiting the enzyme activity. Thirdly, it also reduced the amount of released from phorbor ester-stimulated human neutrophils. PFD alone showed few such effects. These results suggest the possibility that the scavenging effect of the PFD-iron complex contributes to the anti-fibrotic action of PFD used for treating idiopathic pulmonary fibrosis. 相似文献
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Kou S Pan L van Noort D Meng G Wu X Sun H Xu J Lee I 《Biochemical and biophysical research communications》2011,(2):350-355
Reactive oxygen species (ROS) are an important factor in the development of skin lesions in diabetes. A new antioxidant, hydrogen, can selectively neutralize hydroxyl radicals (OH) and peroxynitrite (ONOO−) in cell-free systems, whereas it seldom reacts with other ROS. Fibroblasts are a key component of skin. In the present study, we investigated the protective effects of hydrogen-rich medium on human skin fibroblasts (HSFs) under oxidative stress. Confocal microscopy was used to assay both the intracellular superoxide anion () concentration and the mitochondrial membrane potential (ΔΨ). Cell viability was determined using the Cell Counting Kit-8 (CCK-8). The concentrations of cellular malonaldehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), 8-hydroxy-2′-deoxyguanosine (8-OHdG) and 3-nitrotyrosine (3-NT) were also measured. The results revealed that both mannitol and high glucose could cause oxidative stress in HSFs. Interestingly, the use of a hydrogen-rich medium significantly reduced the level of intracellular , stabilized the ΔΨ and attenuated production of MDA, 8-OHdG and 3-NT which efficiently enhanced the antioxidative defense system and protected the HSFs from subsequent oxidative stress damage. In other words, hydrogen decreased the excessive generation of intracellular and elevated the cellular antioxidative defense. Based on our results, hydrogen may have applications in the treatment of skin diseases caused by diabetes. 相似文献
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The reaction of AuCl3py with Na(pz∗) (pz∗ = pyrazolato, or substituted pyrazolato anion) yields stable dinuclear [cis-AuIIICl2(μ-pz∗)]2 complexes. In the presence of a base, the latter undergo reduction with concomitant transformation of the dinuclear -structure to trinuclear AuI, AuIII (containing trans AuIIICl2-centres) and species. 相似文献
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Halley Caixeta Oliveira 《FEBS letters》2009,583(13):2276-2280
Mitochondria consume nitric oxide (NO) mainly through reaction with superoxide anion (). Here, we analyzed the sources for NO degradation by isolated rat liver mitochondria. Electron leakage from complex III and reverse electron transport to complex I accounted for -dependent NO degradation by mitochondria in the presence of a protonmotive force. Mitochondria incubated with NAD(P)H also presented intense generation and NO degradation rates that were insensitive to respiratory inhibitors and abolished after proteinase treatment. These results suggest that an outer membrane-localized NAD(P)H oxidase activity, in addition to the electron leakage from the respiratory chain, promotes -dependent NO degradation in rat liver mitochondria. 相似文献
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Su-Hua Fan 《Inorganica chimica acta》2009,362(15):5155-4087
Optical sensing of F−, Cl−, Br−, I−, OAc−, , , and by cis-dithiocyanatobis(2,2′-bipyridyl-4,4′-dicarboxylic acid)ruthenium(II) (N3) and bis(tetrabutylammonium) cis-dithiocyanatobis(2,2′-bipyridine-4-COOH,4′-COO−)ruthenium(II) (N719) have been investigated in dimethyl sulfoxide (DMSO), by means of UV-Vis absorption and emission spectrophotometric titrations. Additions of F−, OAc−, and in DMSO solution caused obvious UV-Vis spectral changes with appearance of several isosbestic points, and remarkable emission enhancements along with large blue shifts in emission bands. The values of F−-induced emission intensity enhancement factor (emission quantum yield enhancement factor), I/I0 (φ/φ0), were found to be 40 (86) and 38 (58) for N3 and N719, respectively. No obvious spectral changes were observed upon addition of Cl−, Br−, I−, and in DMSO solutions. Luminescent F− sensing in DMSO/H2O (4:1, v/v) has also been demonstrated to be operative with a luminescence enhancement factor of 12, indicating that N3 is very potential for practical application as fluorescent anion sensor in aqueous solution. An interaction mechanism of anion-induced deprotonation of N3 and N719 was confirmed, and the deprotonation reaction equilibrium constants of N3 and N719 were derived as well. 相似文献
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Séverine Moret 《Inorganica chimica acta》2010,363(3):574-42
The iridium cyclooctadiene complex incorporating a tricyclopentyl phosphine ligand (PCyp3), Ir(η2:η2-C8H12)(PCyp3)Cl, has been prepared. Removal of the chloride from this complex using in CH2Cl2/arene solvent results in dehydrogenation (C-H activation followed by β-H transfer) of one of the alkyl phosphine rings and formation of the complexes (X = H, F) which contain a hybrid phosphine-alkene ligand. These complexes are formed alongside another product (5-20% yield) that has been identified as , which can be prepared in high yield by an alternative, and slightly modified, route. This complex is with a minor isomer that has been tentatively identified as , which results from allylic C-H activation of cyclooctadiene. Addition of H2 to and its isomer in arene solvent (C6H5X, X = F, H) forms the dihydrido η6-arene Ir(III) complexes . In contrast, hydrogenation in CH2Cl2 alone results in the formation of in which the anion is now acting as a ligand through one of its aryl rings. The fluorobenzene complex can be cleanly converted to by addition of the hydrogen acceptor tert-butylethene (tbe). 相似文献
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Hidehiko Kikuchi Futoshi Kuribayashi Tatsuo Nakayama 《Biochemical and biophysical research communications》2010,395(1):61-65
The membrane bound cytochrome b558 composed of large gp91-phox and small p22-phox subunits, and cytosolic proteins p40-, p47- and p67-phox are important components of superoxide ()-generating system in phagocytes and B lymphocytes. A lack of this system in phagocytes is known to cause serious life-threatening infections. Here, we describe that curcumin, a polyphenol responsible for the yellow color of curry spice turmeric, dramatically activates the -generating system during retinoic acid (RA)-induced differentiation of human monoblastic leukemia U937 cells to macrophage-like cells. When U937 cells were cultured in the presence of RA and curcumin, the -generating activity increased more than 4-fold compared with that in the absence of the latter. Semiquantitative RT-PCR showed that co-treatment with RA and curcumin slightly enhanced gene expressions of the five components compared with those of the RA-treatment only. On the other hand, immunoblot analysis revealed that co-treatment with RA and curcumin caused remarkable accumulation of protein levels of p47-phox (to 7-fold) and p67-phox (to 4-fold) compared with those of the RA-treatment alone. These results suggested that curcumin dramatically enhances RA-induced -generating activity via accumulation of cytosolic p47-phox and p67-phox proteins in U937 cells. Therefore, it should have the potential as an effective modifier in therapy of leukemia and/or as an immunopotentiator. 相似文献
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Zhi-Ping Mei 《Journal of theoretical biology》2009,259(3):582-588
Communities of marine phytoplankton consist of cells of many different sizes. The size-structure of these communities often varies predictably with environmental conditions in aquatic systems. It has been hypothesized that physiological differences in nutrient and light requirements and acquisition efficiencies contribute to commonly observed correlations between phytoplankton community size structure and resource availability. Using physiological models we assess how light and nutrient availability can alter the relative growth rates of phytoplankton species of different cell sizes. Our models predict a change in the size dependence of growth rate depending on the severity of limitation by light and nutrient availability. Under conditions of growth-saturated resource supply, phytoplankton growth rate (mol C ) scales with cell volume with a size-scaling exponent of ; light limitation reduces the size-scaling exponent to approximately , and nutrient limitation decreases the exponent to as a consequence of the size-scaling of resource acquisition. Exponents intermediate between and occur under intermediate availability of light and nutrients and depend on the size-scaling of pigment photoacclimation and the size range examined. 相似文献
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Rachel Gilbert 《Inorganica chimica acta》2010,363(7):1462-1468
Unlike other chlorometallate complexes that catalyze the photodecomposition of haloalkanes through photodissociation of a chlorine atom, both and catalyze chloroform decomposition through a process that appears to involve C-H bond breakage from an excited state association complex with chloroform. This would account for the greatly retarded rate of decomposition in CDCl3 and for the generation of CCl4 as a side product. In chloroform, and are in slow equilibrium with each other. The rate for the conversion of - in chloroform at 23 °C obeys the expression (0.03 M−1 s−1) [][Cl−]. The equilibrium constant, K = [][Cl−]2/[]2, was estimated to be 3 × 10−3 M in CHCl3. 相似文献
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Seth Bradford 《Journal of inorganic biochemistry》2009,103(6):871-875
The reactivity of [Cu2+·Lys-Gly-His-Lys-NH2]2+ and [Cu2+·Lys-Gly-His-Lys]+ toward tRNAPhe has been evaluated. The amidated and carboxylate forms of the copper peptides display complex binding behavior with strong and weak sites evident (, for the amide form; and , for the carboxylate form), while Cu2+(aq) yielded and . The time-dependence of the reaction of [Cu2+·Lys-Gly-His-Lys]+ and [Cu2+·Lys-Gly-His-Lys-NH2]2+ with tRNAPhe yielded kobs ∼ 0.075 h−1 for both complexes. HPLC analysis of the reaction products demonstrated guanine as the sole base product. Mass spectrometric data shows a limited number of cleavage fragments with product peak masses consistent with chemistry occurring at a discrete site defined by the structurally contiguous D and TΨC loops, and in a domain where high affinity magnesium centers have previously been observed to promote hydrolysis of the tRNAPhe backbone. This cleavage pattern is more selective than that previously observed by Long and coworkers for nickel complexes of a series of C-terminally amidated peptides (Gly-Gly-His, Lys-Gly-His, and Arg-Gly-His), and may reflect variations in structural recognition and a distinct reaction path by the nickel derivatives. The data emphasizes the optimal positioning of the metal-associated reactive oxygen species, relative to scissile bonds, as a major criterion for development of efficient catalytic nucleases or therapeutics. 相似文献
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The XAFS spectra were measured at around the Ag K-edge of the Ag(I) ion in nitromethane (NM) with a variety of concentrations of pyridine (PY). In NM without PY, the Ag(I) ion is tetrahedrally solvated by four NM molecules similar to those in most solvents. The Ag-O bond length in NM solvent is longer than that in aqueous solution, indicating the low donating ability of NM. The mono-, bis-, tris-, and tetrakis-pyridine complexes are formed in NM by the addition of PY. The EXAFS analyses reveal that the structure of the formed PY complex in NM is linear for Ag(py)(nm)+, linear for , triangular for , and tetrahedral for . The longer Ag-O bond length for Ag(py)(nm)+ than that for and the release of bound NM molecules at the formation of Ag(py)(nm)+ are interpreted to be due to the strong σ donating property of PY. The Ag-N bond length (220 pm) for is intermediate between 216 pm for and 228 pm for . The formation equilibria of and are analyzed on the basis of the changeover of EXAFS spectra as a function of the total concentrations of Ag+ and PY in NM. 相似文献
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