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Using a redox-inert methyl acceptor, we show that betaine-homocysteine S-methyltransferase (BHMT) requires a thiol reducing agent for activity. Short-term exposure of BHMT to reducing agent-free buffer inactivates the enzyme without causing any loss of its catalytic zinc. Activity can be completely restored by the re-addition of a thiol reducing agent. The catalytic zinc of BHMT is bound by three thiolates and one hydroxyl group. Thiol modification experiments indicate that a disulfide bond is formed between two of the three zinc-binding ligands when BHMT is inactive in a reducing agent-free buffer, and that this disulfide can be readily reduced with the concomitant restoration of activity by re-establishing reducing conditions. Long-term exposure of BHMT to reducing agent-free buffer results in the slow, irreversible loss of its catalytic Zn and a corresponding loss of activity. Experiments using the glutamate-cysteine ligase modifier subunit knockout mice Gclm(−/−), which are severely impaired in glutathione synthesis, show that BHMT activity is reduced about 75% in Gclm(−/−) compared to Gclm(+/+) mice. 相似文献
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Rie Hasebe Akio SuzukiTakeshi Yamasaki Motohiro Horiuchi 《Biochemical and biophysical research communications》2014
CD14 deficient (CD14−/−) mice survived longer than wild-type (WT) C57BL/6J mice when inoculated with prions intracerebrally, accompanied by increased expression of anti-inflammatory cytokine IL-10 by microglia in the early stage of infection. To assess the immune regulatory effects of CD14 in detail, we compared the gene expression of pro- and anti-inflammatory cytokines in the brains of WT and CD14−/− mice infected with the Chandler strain. Gene expression of the anti-inflammatory cytokine IL-13 in prion-infected CD14−/− mice was temporarily upregulated at 75 dpi, whereas IL-13 gene expression was not upregulated in prion-infected WT mice. Immunofluorescence staining showed that IL-13 was mainly expressed in neurons of the thalamus at 75 dpi. These results suggest that CD14 can suppress IL-13 expression in neurons during the early stage of prion infection. 相似文献
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Michael J. Vasbinder 《Inorganica chimica acta》2008,361(11):3193-3198
Oxidation of the title complexes with ozone takes place by hydrogen atom, hydride, and electron transfer mechanisms. The reaction with (NH3)4(H2O)RhH2+ is a two electron process, believed to involve hydride transfer with a rate constant k = (2.2 ± 0.2) × 105 M−1 s−1 and an isotope effect kH/kD = 2. The oxidation of (NH3)4(H2O)RhOOH2+ to (NH3)4(H2O)RhOO2+ by an apparent hydrogen atom transfer is quantitative and fast, k = (6.9 ± 0.3) × 103 M−1 s−1, and constitutes a useful route for the preparation of the superoxo complex. The latter is also oxidized by ozone, but more slowly, k = 480 ± 50 M−1 s−1. 相似文献
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Debabrata Chatterjee Anannya Mitra Ayon Sengupta Susan Basak 《Inorganica chimica acta》2005,358(10):2900-2908
The interaction of [PdII(mida)(Cl)]− (1) (mida2− = N-methyliminodiacetate) and [PdII(pydc)(Cl)]− (2) (pydc2− = pyridyl-2,6-dicarboxylate) with adenosine-5′-monophosphate (AMP), inosine-5′-monophosphate (IMP) and glutathione (GSH) was studied kinetically as a function of [L] (L = AMP, IMP, GSH) and [Cl−] and temperatures (10-35 °C) at pH 4.0. The kinetic results suggest that the reaction of 1 and 2 with the 5′-nucleotides (AMP, IMP) is characterized by the hydrolysis of chloro-complexes followed by the aquo-substitution with purine based 5′-nucleotides through its N7 atom. The reaction of 1 and 2 with GSH takes place through the direct chloride replacement with GSH. Kinetic data and activation parameters are interpreted in terms of an associative mechanism and discussed in reference to the data reported earlier. The [PtII(mida)(Cl)]− (3) and [PtII(pydc)(Cl)]− (4) complexes were prepared and allowed to interact with AMP and IMP and their reaction products were characterized by 1H NMR studies. The antitumor activity of 3 and 4 was examined against MCF-7 (breast cancer), NCI-H460 (lung cancer) and SF-268 (CNS) cell lines. 相似文献
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Dorothy I. Mundy Adam M. Lopez Kenneth S. Posey Jen-Chieh Chuang Charina M. Ramirez Philipp E. Scherer Stephen D. Turley 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2014,1841(7):995-1002
Caveolin-1 (Cav-1) is a major structural protein in caveolae in the plasma membranes of many cell types, particularly endothelial cells and adipocytes. Loss of Cav-1 function has been implicated in multiple diseases affecting the cardiopulmonary and central nervous systems, as well as in specific aspects of sterol and lipid metabolism in the liver and intestine. Lungs contain an exceptionally high level of Cav-1. Parameters of cholesterol metabolism in the lung were measured, initially in Cav-1-deficient mice (Cav-1−/−), and subsequently in Cav-1−/− mice that also lacked the lysosomal cholesterol transporter Niemann–Pick C1 (Npc1) (Cav-1−/−:Npc1−/−). In 50-day-old Cav-1−/− mice fed a low- or high-cholesterol chow diet, the total cholesterol concentration (mg/g) in the lungs was marginally lower than in the Cav-1+/+ controls, but due to an expansion in their lung mass exceeding 30%, whole-lung cholesterol content (mg/organ) was moderately elevated. Lung mass (g) in the Cav-1−/−:Npc1−/− mice (0.356 ± 0.022) markedly exceeded that in their Cav-1+/+:Npc1+/+ controls (0.137 ± 0.009), as well as in their Cav-1−/−:Npc1+/+ (0.191 ± 0.013) and Cav-1+/+:Npc1−/− (0.213 ± 0.022) littermates. The corresponding lung total cholesterol contents (mg/organ) in mice of these genotypes were 6.74 ± 0.17, 0.71 ± 0.05, 0.96 ± 0.05 and 3.12 ± 0.43, respectively, with the extra cholesterol in the Cav-1−/−:Npc1−/− and Cav-1+/+:Npc1−/− mice being nearly all unesterified (UC). The exacerbation of the Npc1 lung phenotype and increase in the UC level in the Cav-1−/−:Npc1−/− mice imply a regulatory role of Cav-1 in pulmonary cholesterol metabolism when lysosomal sterol transport is disrupted. 相似文献
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Charina M. Ramirez Adam M. Lopez Lam Q. Le Kenneth S. Posey Arthur G. Weinberg Stephen D. Turley 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2014,1841(1):54-61
Niemann–Pick Type C (NPC) disease is caused by a deficiency of either NPC1 or NPC2. Loss of function of either protein results in the progressive accumulation of unesterified cholesterol in every tissue leading to cell death and organ damage. Most literature on NPC disease focuses on neurological and liver manifestations. Pulmonary dysfunction is less well described. The present studies investigated how Npc1 deficiency impacts the absolute weight, lipid composition and histology of the lungs of Npc1−/− mice (Npc1nih) at different stages of the disease, and also quantitated changes in the rates of cholesterol and fatty acid synthesis in the lung over this same time span (8 to 70 days of age). Similar measurements were made in Npc2−/− mice at 70 days. All mice were of the BALB/c strain and were fed a basal rodent chow diet. Well before weaning, the lung weight, cholesterol and phospholipid (PL) content, and cholesterol synthesis rate were all elevated in the Npc1−/− mice and remained so at 70 days of age. In contrast, lung triacylglycerol content was reduced while there was no change in lung fatty acid synthesis. Despite the elevated PL content, the composition of PL in the lungs of the Npc1−/− mice was unchanged. H&E staining revealed an age-related increase in the presence of lipid-laden macrophages in the alveoli of the lungs of the Npc1−/− mice starting as early as 28 days. Similar metabolic and histologic changes were evident in the lungs of the Npc2−/− mice. Together these findings demonstrate an intrinsic lung pathology in NPC disease that is of early onset and worsens over time. 相似文献
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Chen G Mi J Wu X Luo C Li J Tang Y Li J 《International journal of biological macromolecules》2011,49(4):543-547
Fourier transform infrared (FT-IR) spectroscopic studies (3500-600 cm−1) showed some different bands of chitosan. The absorption at 3439 cm−1 is stretching vibration of -OH and -NH2 bonds, indicating the association of the hydrogen-bond between them. The bands at 1659, 1599 and 1321 cm−1 are attributable to the peaks of stretching vibrations of amide I (ν(CO)), II (δ(N-H)), and the peak of stretching and bending vibrations of III (ν(C-N)) (δ(N-H)). The chitosan showed strong free radical scavenging activities. Pretreatment with chitosan significantly prevented the decrease of antioxidant enzymes activities and the increase of p-JNK at 3 h after renal ischemia and reduced renal tubular epithelial cell apoptosis. 相似文献
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Substitution reaction of fac-[FeII(CN)2(CO)3I]− with triphenylphosphine (PPh3) produced mono phosphine substituted complex cis-cis-[FeII(CN)2(CO)2(PPh3)I]−. Crystal structure of the product showed that carbonyl positioned trans- to iodide was replaced by PPh3. The substitution reaction was monitored by quantitative infrared spectroscopic method, and the rate law for the substitution reaction was determined to be rate = k[[FeII(CN)2(CO)2(PPh3)I]−][PPh3]. Transition state enthalpy and entropy changes were obtained from Eyring equation k = (kBT/h)exp(−ΔH≠/RT + ΔS≠/R) with ΔH≠ = 119(4) kJ mol−1 and ΔS≠ = 102(10) J mol−1 K−1. Positive transition state entropy change suggests that the substitution reaction went through a dissociative pathway. 相似文献
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Dan Ye Illiana Meurs Megumi Ohigashi Kim L.L. Habets Yoshiyuki Kubo Theo J.C. Van Berkel Miranda Van Eck 《Biochemical and biophysical research communications》2010,395(3):387-394
Objectives
To determine the role of macrophage ATP-binding cassette transporter A5 (ABCA5) in cellular cholesterol homeostasis and atherosclerotic lesion development.Methods and results
Chimeras with dysfunctional macrophage ABCA5 (ABCA5−M/−M) were generated by transplantation of bone marrow from ABCA5 knockout (ABCA5−/−) mice into irradiated LDLr−/− mice. In vitro, bone marrow-derived macrophages from ABCA5−M/−M chimeras exhibited a 29% (P < 0.001) decrease in cholesterol efflux to HDL, whereas a 21% (P = 0.07) increase in cholesterol efflux to apoA-I was observed. Interestingly, expression of ABCA1, but not ABCG1, was up-regulated in absence of functional ABCA5 in macrophages. To induce atherosclerosis, the transplanted LDLr−/− mice were fed a high-cholesterol Western-type diet (WTD) for 6, 10, or 18 weeks, allowing analysis of effects on initial as well as advanced lesion development. Atherosclerosis development was not affected in male ABCA5−M/−M chimeras after 6, 10, and 18 weeks WTD feeding. However, female ABCA5−M/−M chimeras did develop significantly (P < 0.05) larger aortic root lesions as compared with female controls after 6 and 10 weeks WTD feeding.Conclusions
ABCA5 influences macrophage cholesterol efflux, and selective disruption of ABCA5 in macrophages leads to increased atherosclerotic lesion development in female LDLr−/− mice. 相似文献14.
A case study on Centaurea gymnocarpa Moris & De Not., a narrow endemic species, was carried out by analyzing its morphological, anatomical, and physiological traits in response to natural habitat stress factors under Mediterranean climate conditions. The results underline that the species is particularly adapted to the environment where it naturally grows. At the plant level, the above-ground/below-ground dry mass (1.73 ± 0.60) shows its investment predominately in the above-ground structure with a resulting total leaf area per plant of 1399 ± 94 cm2. The senescent attached leaves at the base of the plant contribute to limit leaf transpiration by shading soil around the plant. Moreover, the dense C. gymnocarpa leaf pubescence, leaf rolling, the relatively high leaf mass area (LMA = 12.3 ± 1.3 mg cm−2) and leaf tissue density (LTD = 427 ± 44 mg cm−3) contribute to limit leaf transpiration, also postponing leaf death under dry conditions. At the physiological level, a relatively low respiration/photosynthesis ratio (R/PN) in spring results from high R [2.26 ± 0.59 μmol (CO2) m−2 s−1] and PN [12.3 ± 1.5 μmol (CO2) m−2 s−1]. The high photosynthetic nitrogen use efficiency [PNUE = 15.5 ± 0.4 μmol (CO2) g−1 (N) s−1] shows the large amount of nitrogen (N) invested in the photosynthetic machinery of new leaves, associated to a high chlorophyll content (Chl = 35 ± 5 SPAD units). On the contrary, the highest R/PN ratio (1.75 ± 0.19) in summer is due to a significant PN decrease and increase of R in response to drought. The low PNUE [1.5 ± 0.2 μmol (CO2) g−1 (N) s−1] in this season is indicative of a greater N investment in leaf cell walls which may contribute to limit transpiration. On the contrary, the low R/PN ratio (0.05 ± 0.02) in winter is resulting from the limited enzyme activity of the respiratory apparatus [R = 0.23 ± 0.08 μmol (CO2) m−2 s−1] while the low PNUE [3.5 ± 0.2 μmol (CO2) g−1 (N) s−1] suggests that low temperatures additionally limit plant production. The experiment of the imposed water stress confirms that the C. gymnocarpa growth capability is in conformity with the severe conditions of its natural habitat, likewise as it may be the case with others narrow endemic species that have occupied niches with similar extreme conditions. 相似文献
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Se-dependent glutathione peroxidase-1 (GPX1) and Cu,Zn-superoxide dismutase (SOD1) are two major intracellular antioxidant enzymes. The purpose of this study was to elucidate the biochemical mechanisms for the 40% loss of hepatic GPX1 activity in SOD1−/− mice. Compared with the wild type (WT), the SOD1−/− mice showed no change in the total amount of GPX1 protein. However, their total enzyme protein exhibited 31 and 38% decreases (P < 0.05) in the apparent kcat for hydrogen peroxide and tert-butylperoxide (at 2 mM GSH), respectively. Most striking, mass spectrometry revealed two chemical forms of the 47th residue of GPX1: the projected native selenocysteine (Sec) and the Se-lacking dehydroalanine (DHA). The hepatic GPX1 protein of the SOD1−/− mice contained 38% less Sec and 77% more DHA than that of WT and showed aggravated dissociation of the tetramer structure. In conclusion, knockout of SOD1 elevated the conversion of Sec to DHA in the active site of hepatic GPX1, leading to proportional decreases in the apparent kcat and activity of the enzyme protein as a whole. Our data reveal a structural and kinetic mechanism for the in vivo functional dependence of GPX1 on SOD1 in mammals and provide a novel mass spectrometric method for the assay of oxidative modification of the GPX1 protein. 相似文献
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Inoue K Takano H Kaewamatawong T Shimada A Suzuki J Yanagisawa R Tasaka S Ishizaka A Satoh M 《Free radical biology & medicine》2008,45(12):1714-1722
Metallothionein (MT) is a free radical scavenger induced by inflammatory stimuli; however, its roles in inflammation have not been fully investigated. In the present study, we genetically determined the role of MT in ozone (O3)-induced lung inflammation using MT-I/II null (–/–) mice. Subacute (65 h) exposure to O3 (0.3 ppm) induced lung inflammation and enhanced vascular permeability, which was significantly greater in MT(–/–) than in corresponding wild-type mice. Electron microscopically, O3 exposure induced vacuolar degeneration of pulmonary endothelial and epithelial cells, and interstitial edema with focal loss of the basement membrane, which was more prominent in MT(–/–) than in wild-type mice. O3 -induced lung expression of interleukin-6 was significantly greater in MT(–/–) than in wild-type mice; however, lung expression of the chemokines examined was comparable in both genotypes of mice in the presence of O3. Following O3 exposure, the formation of oxidative stress-related molecules/adducts, such as heme oxidase-1, inducible nitric oxide synthase, 8-hydroxy-2′-deoxyguanosine, and nitrotyrosine, in the lung was significantly greater in MT(–/–) than in wild-type mice. Collectively, MT protects against O3-induced lung inflammation, at least partly, via the regulation of pulmonary endothelial and epithelial integrity and its antioxidative property. 相似文献
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An earlier study revealed that 4-day-old mice, but not older mice, were infected with invasive Shigella strains. Here we attempted to determine the underlying mechanism that induces inflammation in the intestines of neonate mice after oral Shigella infection. Wild-type BALB/c mice of different ages (7, 14, and 35 days old) were orally administered GFP-expressing Shigella flexneri 5a M90T strain (5 × 109 CFU) and analyzed for colonization 6 h following infection. We found that Shigella localized in the epithelium, lamina propria, and crypt regions of the small intestines of 7-day-old BALB/c mice. Microarray analysis revealed that expression levels of cryptdin and various types of cryptdin-related mRNA (e.g., cryptrs-2, -5, -7, -12 and lysozyme) in the small intestines were significantly lower in 7-day-old than in older mice regardless of Shigella infection status. Interestingly, matrix metalloprotease-7 (matrilysin)-deficient (MAT−/−) mice of B6 background had more colonies and more severe symptoms of inflammation in the intestines than did wild-type B6 mice after oral Shigella challenge. This suggests that cryptdin-related antimicrobial molecules are indispensable for efficient protection against oral Shigella infection. 相似文献
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The nitrosyl complex [Cr(dmso)5(NO)](PF6)2 (1) (dmso = dimethyl sulfoxide) has been prepared by the solvolysis of [Cr(NCCH3)5(NO)](PF6)2 in neat dmso. The optical absorption spectrum of 1 in dmso shows maxima at 734, 567, 450, 413, and 337 nm. Continuous photolysis of 1 with λ = 365-580 nm light in dmso solution results in a release of NO with quantum yield, Φ, in the range 0.034-0.108 mol Einstein−1. Irradiation of a deoxygenated CH3CN solution of [Cr(NCCH3)5(NO)](PF6)2 in the presence of excess of [Fe(S2CNEt2)2] results in a transfer of NO to the iron centre as shown from the characteristic EPR spectrum of [Fe(S2CNEt2)2(NO)] with Aiso(14N) = 12.2 × 10−4 cm−1. The EPR parameters of 1 were determined: giso, g‖ and g⊥ : 1.96725, 1.91881(4) and 1.992763(2); Aiso(53Cr), A‖ (53Cr) and A⊥(53Cr): 22.8 × 10−4, 39 × 10−4 and 15.8 × 10−4 cm−1; Aiso(14N), A‖ (14N) and A⊥(14N): 5.9 × 10−4, 2 × 10−4 and 7.540(4) × 10−4 cm−1. 相似文献
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Cariou B van Harmelen K Duran-Sandoval D van Dijk T Grefhorst A Bouchaert E Fruchart JC Gonzalez FJ Kuipers F Staels B 《FEBS letters》2005,579(19):4076-4080
The farnesoid X receptor (FXR) has been suggested to play a role in gluconeogenesis. To determine whether FXR modulates the response to fasting in vivo, FXR-deficient (FXR−/−) and wild-type mice were submitted to fasting for 48 h. Our results demonstrate that FXR modulates the kinetics of alterations of glucose homeostasis during fasting, with FXR−/− mice displaying an early, accelerated hypoglycaemia response. Basal hepatic glucose production rate was lower in FXR−/− mice, together with a decrease in hepatic glycogen content. Moreover, hepatic PEPCK gene expression was transiently lower in FXR−/−mice after 6 h of fasting and was decreased in FXR−/−hepatocytes. FXR therefore plays an unexpected role in the control of fuel availability upon fasting. 相似文献
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Chih-Hao Tang Yun-Ren Lai Yi-Chung Chen Chen-Hsiu Li Yu-Fen Lu Hung-Yen Chen Huang-Wei Lien Chung-Hsiang Yang Chang-Jen Huang Chen-Yi Wang Cheng-Fu Kao Sheng-Ping L. Hwang 《Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms》2014,1839(6):425-437
AGR2 is a member of the protein disulfide isomerase (PDI) family, which is implicated in cancer cell growth and metastasis, asthma, and inflammatory bowel disease. Despite the contributions of this protein to several biological processes, the regulatory mechanisms controlling expression of the AGR2 gene in different organs remain unclear. Zebrafish anterior gradient 2 (agr2) is expressed in several organs, including the otic vesicles that contain mucus-secreting cells. To elucidate the regulatory mechanisms controlling agr2 expression in otic vesicles, we generated a Tg(− 6.0 k agr2:EGFP) transgenic fish line that expressed EGFP in a pattern recapitulating that of agr2. Double immunofluorescence studies were used to demonstrate that Agr2 and GFP colocalize in the semicircular canals and supporting cells of all sensory patches in the otic vesicles of Tg(− 6.0 k agr2:EGFP) embryos. Transient/stable transgenic analyses coupled with 5′-end deletion revealed that a 100 bp sequence within the − 2.6 to − 2.5 kbp region upstream of agr2 directs EGFP expression specifically in the otic vesicles. Two HMG-binding motifs were detected in this region. Mutation of these motifs prevented EGFP expression. Furthermore, EGFP expression in the otic vesicles was prevented by knockdown of the sox10 gene. This corresponded with decreased agr2 expression in the otic vesicles of sox10 morphants during different developmental stages. Electrophoretic mobility shift assays were used to show that Sox10 binds to HMG-binding motifs located within the − 2.6 to − 2.5 kbp region upstream of agr2. These results demonstrate that agr2 expression in the otic vesicles of zebrafish embryos is regulated by Sox10. 相似文献