共查询到20条相似文献,搜索用时 15 毫秒
1.
Qun Zeng Huang 《Carbohydrate research》2010,345(1):115-119
A new supermolecular assembly crystal, [C6H8N2]6H3[PW12O40]·2H2O (DMB-PWA), was synthesized with phosphotungstic acid (PWA) and 1,2-diaminobenzene (DMB) under hydrothermal conditions and was characterized by Fourier-transform infrared spectra (FTIR) and single-crystal X-ray diffraction analysis. DMB-PWA could effectively catalyze oxidative degradation of chitosan with H2O2 in the heterogeneous phase. The optimum degradation conditions were determined by orthogonal tests as follows: amount of chitosan 1.00 g, 30% (wt %); H2O2, 3.0 mL; dosage of catalyst, 0.06 g; reaction temperature, 85 °C; and reaction time, 30 min. The water-soluble chitosan with a viscosity-average molecular weight (Mv) of 4900 was obtained under the optimum degradation conditions and was characterized by FTIR, ultraviolet-visible diffuse reflection spectra (UV-vis DRS), and X-ray powder diffraction analysis. 相似文献
2.
James A.G. Crispo Matthew Piché Dominique R. Ansell Joseph K. Eibl Isabella T. Tai Aseem Kumar Gregory M. Ross T.C. Tai 《Biochemical and biophysical research communications》2010,393(4):773-778
Neurodegenerative disorders are a class of diseases that have been linked to apoptosis induced by elevated levels of reactive oxygen species (ROS). ROS activates the apoptotic cascade through mitochondrial dysfunction and damage to lipids, proteins and DNA. Recently, fruit and tea-derived polyphenols have been found to be beneficial in decreasing oxidative stress and increasing overall health. Further, polyphenols including epigallocatechin gallate (EGCG) have been reported to inhibit apoptotic signaling and increase neural cell survival. In an effort to better understand the beneficial properties associated with polyphenol consumption, the aim of this study was to explore the neuroprotective effects of EGCG, methyl gallate (MG), gallic acid (GA) and N-acetylcysteine (NAC) on H2O2-induced apoptosis in PC12 cells and elucidate potential protective mechanisms. Cell viability data demonstrates that MG and NAC pre-treatments significantly increase viability of H2O2-stressed cells, while pre-treatments with EGCG and GA exacerbates stress. Quantitation of apoptosis and mitochondrial membrane potential shows that MG pre-treatment prevents mitochondria depolarization, however does not inhibit apoptosis and is thus evidence that MG can inhibit mitochondria-mediated apoptosis. Subsequent analysis of DNA degradation and caspase activation reveals that MG inhibits activation of caspase 9 and has a partial inhibitory effect on DNA degradation. These findings confirm the involvement of both intrinsic and extrinsic apoptotic pathways in H2O2-induced apoptosis and suggest that MG may have potential therapeutic properties against mitochondria-mediated apoptosis. 相似文献
3.
Nitroxyl (HNO) has received recent and significant interest due to its novel and potentially important pharmacology. However, the chemical/biochemical mechanism(s) responsible for its biological activity remain to be established. Some of the most important biological targets for HNO are thiols and thiol proteins. Consistent with this, it was recently reported that HNO inhibits the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a protein with a catalytically important cysteine thiol at its active site. Interestingly, it was reported that intracellular GAPDH inhibition occurred without significantly altering the cellular thiol redox status of glutathione. Herein, the nature of this reaction specificity was examined. HNO is found to irreversibly inhibit GAPDH in a manner that can be protected against by one of its substrates, glyceraldehyde-3-phosphate (G-3-P). These results are consistent with the idea that HNO has the ability to react with and oxidize a variety of intracellular thiols and the ease or facility of cellular re-reduction of the thiol targets can determine the target specificity. 相似文献
4.
Omer Kabil Nicole MotlRuma Banerjee 《Biochimica et Biophysica Acta - Proteins and Proteomics》2014,1844(8):1355-1366
Hydrogen sulfide (H2S) has emerged as an important gaseous signaling molecule that is produced endogenously by enzymes in the sulfur metabolic network. H2S exerts its effects on multiple physiological processes important under both normal and pathological conditions. These functions include neuromodulation, regulation of blood pressure and cardiac function, inflammation, cellular energetics and apoptosis. Despite the recognition of its biological importance and its beneficial effects, the mechanism of H2S action and the regulation of its tissue levels remain unclear in part owing to its chemical and physical properties that render handling and analysis challenging. Furthermore, the multitude of potential H2S effects has made it difficult to dissect its signaling mechanism and to identify specific targets. In this review, we focus on H2S metabolism and provide an overview of the recent literature that sheds some light on its mechanism of action in cellular redox signaling in health and disease. This article is part of a Special Issue entitled: Thiol-Based Redox Processes. 相似文献
5.
Interleukin IL-17F was expressed in colon epithelial cells and showed multiple functions in colon tumorigenesis. However, the role of IL-17F in colon cancer cell cycle progression remains unclear. In this study, we analyzed the effects of IL-17F on oxidant-induced cell cycle shift in human colon cancer cells. IL-17F overexpressing and wildtype HCT116 cells were challenged with H2O2. Cell cycle distribution analysis showed IL-17F attenuated H2O2-induced G2/M phase arrest by inhibiting S to G2/M transition. We further checked expression levels of two critical cell cycle regulators p21 and p27. The results showed that IL-17F could inhibit H2O2 induced p27 up-regulation. Meanwhile, IL-17F could increase the phosphorylation of p38 after H2O2 treatment. The regulations of p27 level and p38 activity may contribute to the impaired G2/M phase arrest by IL-17F. Taken together, our findings extend IL-17F as an important factor in colon cancer development and provide new insight into the signaling pathway. 相似文献
6.
Jin Oshikawa Norifumi Urao Ha Won Kim Nihal Kaplan Masooma Razvi Ronald McKinney Leslie B. Poole Tohru Fukai Masuko Ushio-Fukai 《PloS one》2010,5(4)
Reactive oxygen species (ROS), in particular, H2O2, is essential for full activation of VEGF receptor2 (VEGFR2) signaling involved in endothelial cell (EC) proliferation and migration. Extracellular superoxide dismutase (ecSOD) is a major secreted extracellular enzyme that catalyzes the dismutation of superoxide to H2O2, and anchors to EC surface through heparin-binding domain (HBD). Mice lacking ecSOD show impaired postnatal angiogenesis. However, it is unknown whether ecSOD-derived H2O2 regulates VEGF signaling. Here we show that gene transfer of ecSOD, but not ecSOD lacking HBD (ecSOD-ΔHBD), increases H2O2 levels in adductor muscle of mice, and promotes angiogenesis after hindlimb ischemia. Mice lacking ecSOD show reduction of H2O2 in non-ischemic and ischemic limbs. In vitro, overexpression of ecSOD, but not ecSOD-ΔHBD, in cultured medium in ECs enhances VEGF-induced tyrosine phosphorylation of VEGFR2 (VEGFR2-pY), which is prevented by short-term pretreatment with catalase that scavenges extracellular H2O2. Either exogenous H2O2 (<500 µM), which is diffusible, or nitric oxide donor has no effect on VEGF-induced VEGFR2-pY. These suggest that ecSOD binding to ECs via HBD is required for localized generation of extracellular H2O2 to regulate VEGFR2-pY. Mechanistically, VEGF-induced VEGFR2-pY in caveolae/lipid rafts, but non-lipid rafts, is enhanced by ecSOD, which localizes at lipid rafts via HBD. One of the targets of ROS is protein tyrosine phosphatases (PTPs). ecSOD induces oxidation and inactivation of both PTP1B and DEP1, which negatively regulates VEGFR2-pY, in caveolae/lipid rafts, but not non-lipid rafts. Disruption of caveolae/lipid rafts, or PTPs inhibitor orthovanadate, or siRNAs for PTP1B and DEP1 enhances VEGF-induced VEGFR2-pY, which prevents ecSOD-induced effect. Functionally, ecSOD promotes VEGF-stimulated EC migration and proliferation. In summary, extracellular H2O2 generated by ecSOD localized at caveolae/lipid rafts via HBD promotes VEGFR2 signaling via oxidative inactivation of PTPs in these microdomains. Thus, ecSOD is a potential therapeutic target for angiogenesis-dependent cardiovascular diseases. 相似文献
7.
Rachel Benisty Aharon Yehonatan Cohen Alexandra Feldman Zvi Cohen Nurith Porat 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2010,1801(9):1098-1104
FabF elongation condensing enzyme is a critical factor in determining the spectrum of products produced by the FASII pathway. Its active site contains a critical cysteine-thiol residue, which is a plausible target for oxidation by H2O2. Streptococcus pneumoniae produces exceptionally high levels of H2O2, mainly through the conversion of pyruvate to acetyl-P via pyruvate oxidase (SpxB). We present evidence showing that endogenous H2O2 inhibits FabF activity by specifically oxidizing its active site cysteine-thiol residue. Thiol trapping methods revealed that one of the three FabF cysteines in the wild-type strain was oxidized, whereas in an spxB mutant, defective in H2O2 production, none of the cysteines was oxidized, indicating that the difference in FabF redox state originated from endogenous H2O2. In vitro exposure of the spxB mutant to various H2O2 concentrations further confirmed that only one cysteine residue was susceptible to oxidation. By blocking FabF active site cysteine with cerulenin we show that the oxidized cysteine was the catalytic one. Inhibition of FabF activity by either H2O2 or cerulenin resulted in altered membrane fatty acid composition. We conclude that FabF activity is inhibited by H2O2 produced by S. pneumoniae. 相似文献
8.
用流式细胞计(flow cytometry,FCM)测定H2O2损伤后的红细胞(RBC)与IgG的结合能力,并直接检测细胞自发荧光的变化,以研究H2O2对RBC抗原性和脂质过氧化(LPO)荧光产物生成的影响.结果表明RBC抗原性和自发荧光变化与H2O2浓度和作用时间有关,抗原性变化对H2O2更敏感,比引起自发荧光明显增强所需H2O2浓度低两个数量级;还发现了RBC抗原性和自发荧光的变化与细胞的散射光有相关性. 相似文献
9.
10.
Irene Mavelli Maria Rosa Ciriolo Giuseppe Rotilio 《Biochemical and biophysical research communications》1983,117(3):677-681
Multiple electrophoretic bands, with RF identical to the natural molecular variants, are produced by treatment of purified Cu, Zn Superoxide dismutase with either H2O2 or ascorbate plus Fe(III) EDTA. The ascorbate reaction is also due to H2O2 since it is inhibited by catalase. However while H2O2 inactivates the enzyme, the electromorphs produced by ascorbate-Fe(III) EDTA have only slightly less activity than the native enzyme and this property parallels the natural situation. It is concluded that oxidative aging can be responsible for the multiple molecular variants of the natural enzyme, under conditions where the oxidant attack is preferentially directed to amino acid side chains outside the active site. Such conditions may occur when a metal ion coordinated to the protein surface undergoes a redox cycle with biological reductants, like ascorbate. 相似文献
11.
Zhenhua Jia Baohong Zou Hansong Dong 《Biochemical and biophysical research communications》2010,396(2):522-527
Quercetin is a potent antioxidant and has been extensively used as a therapy intervention to prevent age-associated diseases. However, emerging studies showed it can also act as a prooxidant and induce H2O2 under certain conditions. In the current study, our results showed that quercetin contributed to the pathogen resistance in Arabidopsis thaliana (Arabidopsis) in response to the infection of virulent strain Pseudomonas syringae pv. Tomato DC3000 (Pst). Various defense responses, such as H2O2 burst, callose deposition, cell death, PR1 (pathogenesis-related 1) and PAL1 (Phe ammonia-lyase 1) gene expression, have been investigated in quercetin-pretreated Pst-inoculated Arabidopsis Col-0 and there was a strong defensive response in quercetin-pretreated Arabidopsis against virulent Pst. However, with the presence of catalase, the protective effects of quercetin on pathogen resistance to virulent Pst disappeared in Arabidopsis, suggesting that H2O2 may play a key role in plant defense responses. In addition, we confirmed that quercetin did not show any beneficial effect on pathogen-free leaves in Arabidopsis, indicating that pathogen challenge is also required to induce the defense responses in quercetin-pretreated Arabidopsis. Furthermore, strong defense responses have been observed in quercetin-pretreated Arabidopsis mutant jar1, ein2, and abi1-2 under Pst challenge, whereas no protective effect has been observed in quercetin-pretreated Arabidopsis mutant NahG and npr1. These findings indicate that quercetin induces the resistance to Pst in Arabidopsis via H2O2 burst and involvement of SA and NPR1. 相似文献
12.
Kseniya N. MarkvichevaDmitry S. Bilan Natalia M. MishinaAndrey Yu. Gorokhovatsky Leonid M. VinokurovSergey Lukyanov Vsevolod V. Belousov 《Bioorganic & medicinal chemistry》2011,19(3):1079-1084
Hydrogen peroxide is an important second messenger controlling intracellular signaling cascades by selective oxidation of redox active thiolates in proteins. Changes in intracellular [H2O2] can be tracked in real time using HyPer, a ratiometric genetically encoded fluorescent probe. Although HyPer is sensitive and selective for H2O2 due to the properties of its sensing domain derived from the Escherichia coli OxyR protein, many applications may benefit from an improvement of the indicator’s dynamic range. We here report HyPer-2, a probe that fills this demand. Upon saturating [H2O2] exposure, HyPer-2 undergoes an up to sixfold increase of the ratio F500/F420 versus a threefold change in HyPer. HyPer-2 was generated by a single point mutation A406V from HyPer corresponding to A233V in wtOxyR. This mutation was previously shown to destabilize interface between monomers in OxyR dimers. However, in HyPer-2, the A233V mutation stabilizes the dimer and expands the dynamic range of the probe. 相似文献
13.
Shuna Sun Xiaohua LiGuanxin Zhang Huimin MaDeqing Zhang Zhijuan Bao 《Biochimica et Biophysica Acta (BBA)/General Subjects》2006
Singlet oxygen (1O2) has been shown to play an important role in salivary defense system, but its generation process and level from human saliva remain uncertain due to the lack of a reliable detection method. We have previously reported 4,4′(5′)-bis[2-(9-anthryloxy)ethylthio]tetrathiafulvalene (BAET) as a novel chemiluminescence probe for 1O2. In this work, the probe is successfully used to characterize H2O2-dependent generation of 1O2 from saliva in real time. However, the yield of 1O2 is found to be very low, for example, being about 0.13 nmol from 200 μL saliva in the presence of 1 mM of hydrogen peroxide over a 5-s reaction period. The result is also compared with that obtained with another 1O2 probe 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-a]pyrazin-3-one (CLA), demonstrating that, besides 1O2, the other reactive oxygen species such as hydroxyl radical may also be involved in the reaction of saliva with H2O2. Furthermore, the present study shows that the selectivity of BAET for 1O2 is much higher than that of CLA and thus BAET is highly suited for the detection of 1O2 in the presence of other reactive oxygen species in biological systems. 相似文献
14.
Catalase is a homo-tetrameric enzyme that has its heme active site deeply buried inside the protein. Its only substrate, hydrogen peroxide (H2O2), reaches the heme through a 45 Å-long channel. Large-subunit catalases, but not small-subunit catalases, have a loop (gate loop) that interrupts the major channel. Two accesses lead to a gate that opens the final section of the channel to the heme; gates from the R-related subunits are interconnected. Using molecular dynamic simulations of the Neurospora crassa catalase-1 tetramer in a box of water (48,600 molecules) or 6 M H2O2, it is shown that the number of H2O2 molecules augments at the surface of the protein and in the accesses to the gate and the final section of the channel. Increase in H2O2 is due to the prevalence and distribution of amino acids that have an increased residency for H2O2 (mainly histidine, proline and charged residues), which are localized at the protein surface and the accesses to the gate. In the section of the channel from the heme to the gate, turnover rate of water molecules was faster than for H2O2 and increased residence sites for water and H2O2 were determined. In the presence of H2O2, the exclusion of water molecules from a specific site suggests a mechanism that could contend with the competing activity of water, allowing for catalase high kinetic efficiency. 相似文献
15.
Yan Li Heng Yin Qing Wang Xiaoming Zhao Yuguang Du Fenglan Li 《Carbohydrate polymers》2009,75(4):612-617
NO (nitric oxide) and H2O2 (hydrogen peroxide) are important signaling molecule in plants. Brassica napus L. was used to understand oligochitosan inducing production of NO (nitric oxide) and H2O2 (hydrogen peroxide) and their physiological function. The result showed that the production of NO and H2O2 in epidermal cells of B. napus L. was induced with oligochitosan by fluorescence microscope. And it was proved that there was an interaction between NO and H2O2 with L-NAME (NG-nitro-l-arg-methyl eater), which is an inhibitor of NOS (NO synthase) in mammalian cells that also inhibits plant NO synthesis, and CAT (catalase), which is an important H2O2 scavenger, respectively. It was found that NO and H2O2 induced by oligochitosan took part in inducing reduction in stomatal aperture and LEA protein gene expression of leaves of B. napus L. All these results showed that oligochitosan have potential activities of improving resistance to water stress. 相似文献
16.
Pyotr A. Tyurin-Kuzmin Nadezhda D. Zhdanovskaya Anna A. Sukhova George D. Sagaradze Eugene A. Albert Ludmila V. Ageeva George V. Sharonov Alexander V. Vorotnikov Vsevolod A. Tkachuk 《PloS one》2016,11(4)
Platelet derived growth factor (PDGF) orchestrates wound healing and tissue regeneration by regulating recruitment of the precursor mesenchymal stromal cells (MSC) and fibroblasts. PDGF stimulates generation of hydrogen peroxide that is required for cell migration, but the sources and intracellular targets of H2O2 remain obscure. Here we demonstrate sustained live responses of H2O2 to PDGF and identify PKB/Akt, but not Erk1/2, as the target for redox regulation in cultured 3T3 fibroblasts and MSC. Apocynin, cell-permeable catalase and LY294002 inhibited PDGF-induced migration and mitotic activity of these cells indicating involvement of PI3-kinase pathway and H2O2. Real-time PCR revealed Nox4 and Duox1/2 as the potential sources of H2O2. Silencing of Duox1/2 in fibroblasts or Nox4 in MSC reduced PDGF-stimulated intracellular H2O2, PKB/Akt phosphorylation and migration, but had no such effect on Erk1/2. In contrast to PDGF, EGF failed to increase cytoplasmic H2O2, phosphorylation of PKB/Akt and migration of fibroblasts and MSC, confirming the critical impact of redox signaling. We conclude that PDGF-induced migration of mesenchymal cells requires Nox4 and Duox1/2 enzymes, which mediate redox-sensitive activation of PI3-kinase pathway and PKB/Akt. 相似文献
17.
M. C. ROMERO-PUERTAS M. RODRÍGUEZ-SERRANO F. J. CORPAS M. GÓMEZ L. A. DEL RÍO & L. M. SANDALIO 《Plant, cell & environment》2004,27(9):1122-1134
Cadmium is a toxic metal that produces disturbances in plant antioxidant defences giving rise to oxidative stress. The effect of this metal on H2O2 and O2·? production was studied in leaves from pea plants growth for 2 weeks with 50 µm Cd, by histochemistry with diaminobenzidine (DAB) and nitroblue tetrazolium (NBT), respectively. The subcellular localization of these reactive oxygen species (ROS) was studied by cytochemistry with CeCl3 and Mn/DAB staining for H2O2 and O2·?, respectively, followed by electron microscopy observation. In leaves from pea plants grown with 50 µm CdCl2 a rise of six times in the H2O2 content took place in comparison with control plants, and the accumulation of H2O2 was observed mainly in the plasma membrane of transfer, mesophyll and epidermal cells, as well as in the tonoplast of bundle sheath cells. In mesophyll cells a small accumulation of H2O2 was observed in mitochondria and peroxisomes. Experiments with inhibitors suggested that the main source of H2O2 could be a NADPH oxidase. The subcellular localization of O2·? production was demonstrated in the tonoplast of bundle sheath cells, and plasma membrane from mesophyll cells. The Cd‐induced production of the ROS, H2O2 and O2·?, could be attributed to the phytotoxic effect of Cd, but lower levels of ROS could function as signal molecules in the induction of defence genes against Cd toxicity. Treatment of leaves from Cd‐grown plants with different effectors and inhibitors showed that ROS production was regulated by different processes involving protein phosphatases, Ca2+ channels, and cGMP. 相似文献
18.
Vanderlei Folmer Nuno Pedroso Sílvia C.D.N. Lopes Luísa Cyrne 《生物化学与生物物理学报:生物膜》2008,1778(4):1141-1147
In Saccharomyces cerevisiae, the diffusion rate of hydrogen peroxide (H2O2) through the plasma membrane decreases during adaptation to H2O2 by means of a mechanism that is still unknown. Here, evidence is presented that during adaptation to H2O2 the anisotropy of the plasma membrane increases. Adaptation to H2O2 was studied at several times (15min up to 90min) by applying the steady-state H2O2 delivery model. For wild-type cells, the steady-state fluorescence anisotropy increased after 30min, or 60min, when using 2-(9-anthroyloxy) stearic acid (2-AS), or diphenylhexatriene (DPH) membrane probe, respectively. Moreover, a 40% decrease in plasma membrane permeability to H2O2 was observed at 15min with a concomitant two-fold increase in catalase activity. Disruption of the ergosterol pathway, by knocking out either ERG3 or ERG6, prevents the changes in anisotropy during H2O2 adaptation. H2O2 diffusion through the plasma membrane in S. cerevisiae cells is not mediated by aquaporins since the H2O2 permeability constant is not altered in the presence of the aquaporin inhibitor mercuric chloride. Altogether, these results indicate that the regulation of the plasma membrane permeability towards H2O2 is mediated by modulation of the biophysical properties of the plasma membrane. 相似文献
19.
《Microbes and infection / Institut Pasteur》2009,11(5):537-544
Duox proteins are members of the NADPH oxidase (Nox) family and are responsible for hydrogen peroxide (H2O2) production by various tissue types including bronchial and intestinal mucosae. The antimicrobial killing role of H2O2 in leukocytes and macrophages is generally considered as the paradigm of its function. We investigated here the positive role of H2O2 in the prevention of cellular invasion by Salmonella. We show that H2O2, under conditions that preserved bacterial growth, has a repellent effect on Salmonella motility on agar plates. In addition, H2O2 produced by PCCl3, a rat thyroid cell line, reduces bacterial invasion of the cells by around 40%. To test whether the observed phenotype is attributable to H2O2 production, we constructed a CHO stable cell line expressing Duox2 protein at the cell surface (CHO-D2). The transfected cells produce a high amount of H2O2. Upon infection with Salmonella, the invasion of CHO-D2 cells was reduced by up to 60%. In both PCCl3 and CHO expressing Duox2 cells, normal invasion was restored upon incubation with catalase. Our data suggest that H2O2 at reduced concentrations acts as a repellent for bacteria, keeping them away from cells, a situation that could naturally prevent mucosal cells infection in vivo. 相似文献
20.
Ge Wang 《Inorganica chimica acta》2005,358(4):933-940
Adding one equivalent of H2O2 to compounds of stoichiometry MoCl2(O)2(OPR3)2, OPR3 = OPMePh2 or OPPh3, leads to the formation of oxo-peroxo compounds MoCl2(O)(O2)(OPR3)2. The compound MoCl2(O)(O2)(OPMePh2)2 crystallized with an unequal disorder, 63%:37%, between the oxo and peroxo ligands, as verified by single-crystal X-ray diffractometry, and can be isolated in reasonable yields. MoCl2(O)(O2)(OPPh3)2, was not isolated in pure form, co-crystallized with MoCl2(O)2(OPPh3)2 in two ratios, 18%:82% and 12%:88%, respectively, and did not contain any disorder in the arrangement of the oxo and peroxo groups. These complexes accomplish the isomerization of various allylic alcohols. A mechanism of this reaction has been constructed based on 18O isotopic studies and involves exchange between the alcohol and metal bonded O atoms. 相似文献