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31.
《Journal of Coordination Chemistry》2012,65(22):3843-3858
Five Mn(III) nitrate complexes have been synthesized from dianionic hexadentate Schiff bases obtained by the condensation of 3-ethoxy-2-hydroxybenzaldehyde with different diamines. The complexes have been characterized by elemental analysis, ESI mass spectrometry, IR and 1H NMR spectroscopy, r. t. magnetic, and molar conductivity measurements. Parallel-mode EPR spectroscopy of 1 is also reported. Ligand H2L3 and complexes [MnL1(H2O)2](NO3)(CH3OH) (1), [MnL3(H2O)2]2(NO3)2(CH3OH)(H2O) (3), and [MnL4(H2O)2](NO3)(H2O)2 (4) were crystallographically characterized. The X-ray structures show the self-assembly of the Mn(III)–Schiff base complexes through µ-aquo bridges between neighboring axial water molecules and also by π–π stacking interactions, establishing dimeric and polymeric structures. The peroxidase and catalase activities of the complexes have been studied. Complexes with the shorter spacer between the imine groups (1–2) behave as better peroxidase and catalase mimics, probably due to their ability to coordinate the hydrogen peroxide substrate to manganese. 相似文献
32.
异烟肼(Isoniazid, INH)是最常用的一线抗结核药物之一。据报道,人体内高浓度的异烟肼可导致癫痫, 肝功能衰竭, 甚至死亡。因此,研究异烟肼对人血清白蛋白(HSA)和过氧化氢酶(CAT)的结构和活性的潜在结合影响有利于评估其毒性和副作用。在模拟生理条件下,利用多种荧光光谱和分子对接技术研究INH与HSA和CAT之间的相互作用。所有荧光数据均进行了内滤光校正以获得更准确的结合参数。结果表明,INH-HSA和INH-CAT体系的猝灭常数(Ksv)随着温度的升高而降低,表明INH对HSA及CAT的荧光猝灭机理为静态猝灭。利用紫外-可见吸收光谱、同步荧光光谱、和圆二色(CD)光谱法研究了INH对HSA和CAT构象的影响。结果发现,INH可改变色氨酸残基的微环境并降低HSA和CAT中α-螺旋结构,导致蛋白质结构发生伸展,进而可能影响其生理功能。分子对接结果表明,INH与HSA的结合位点位于HSA的site Ⅰ,ⅡA子域。INH可以进入CAT中β-折叠的桶状空腔,从而抑制CAT的活性。Hill系数结果表明,INH与左氧氟沙星(LVFX,一种安全有效的二线抗结核药物,与其他抗结核药物联合使用可以提高抗结核疗效)之间存在药物协同性,促进INH与HSA的相互作用。另外,CD光谱测定表明INH与LVFX的协同作用改变HSA的二级结构,使α-螺旋结构降低约7.9%。该研究探讨了INH与HSA和CAT之间的结合作用和毒性机制,为INH的安全使用提供重要依据。 相似文献
33.
The object of this study is to investigate the effects of 50-GHz microwave radiation on the brain of Wistar rats. Male rats
of the Wistar strain were used in the study. Animals of 60-day age were divided into two groups—group 1, sham-exposed, and
group 2, experimental (microwave-exposed). The rats were housed in a temperature-controlled room (25 °C) with constant humidity
(40–50%) and received food and water ad libitum. During exposure, rats were placed in Plexiglas cages with drilled ventilation
holes and kept in an anechoic chamber. The animals were exposed for 2 h a day for 45 days continuously at a power level of
0.86 μW/cm2 with nominal specific absorption rate 8.0 × 10−4 w/kg. After the exposure period, the rats were killed and homogenized, and protein kinase C (PKC), DNA double-strand break,
and antioxidant enzyme activity [superoxides dismutase (SOD), catalase, and glutathione peroxidase (GPx)] were estimated in
the whole brain. Result shows that the chronic exposure to these radiations causes DNA double-strand break (head and tail
length, intensity and tail migration) and a significant decrease in GPx and SOD activity (p = <0.05) in brain cells, whereas catalase activity shows significant increase in the exposed group of brain samples as compared
with control (p = <0.001). In addition to these, PKC decreased significantly in whole brain and hippocampus (p < 0.05). All data are expressed as mean ± standard deviation. We conclude that these radiations can have a significant effect
on the whole brain. 相似文献
34.
The dinuclear Mn complex (Et3NH)2[TPA2Mn2(μ-Cl)2](ClO4)4 (I) was synthesized and characterized. Complex I was obtained from the reaction between MnCl2 and [H3TPA](ClO4)3 in MeOH. Structural analysis of I showed the two Mn(II) atoms are bridged by two chloride ligands, forming a bis(μ-chloro)dimanganese core. The [Mn2(μ-Cl)2]2+ core, with a Mn–Mn distance of 3.521(2) Å, is similar to the active site found in chloride-inhibited Mn catalase. EPR and temperature-dependent magnetic susceptibility measurements of complex I showed an antiferromagnetic interaction between the two S = 5/2 Mn centers with an exchange parameter J = −8.8 cm−1. Catalytic activity of H2O2 dismutation was measured for complex I and compared with other related complexes. Kinetic parameters of H2O2 dismutation were obtained and a possible catalytic mechanism of complex I, related to chloride-inhibited Mn catalase, was suggested. 相似文献
35.
Antioxidant potentials and ajmalicine accumulation in Catharanthus roseus after treatment with giberellic acid 总被引:3,自引:3,他引:0
Jaleel CA Gopi R Manivannan P Sankar B Kishorekumar A Panneerselvam R 《Colloids and surfaces. B, Biointerfaces》2007,60(2):195-200
Changes in antioxidant potentials and indole alkaloid, ajmalicine, production were studied in Catharanthus roseus (L.) G. Don. plants under treatment with gibberellic acid (GA(3)). The GA(3) treatments were given in two ways, foliar spray and soil drenching methods on 30, 45, 60 and 75 days after planting (DAP). The plants were uprooted randomly on 90 DAP and separated into root, stem and leaves and used for analyses. The antioxidant potential was studied in terms of non-enzymatc antioxidant molecules like ascorbic acid (AA), alpha-tocopherol (alpha-toc) and reduced glutathione (GSH) and activities of antioxidant enzyme, viz., superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT). The alkaloid ajmalicine was extracted and estimated from roots of both control and treated plants. It was found that, GA(3) has a profound effect upon the antioxidant potentials and it caused a significant enhancement in the production of ajmalicine when compared to untreated control as well as foliar-sprayed plants. There was no significant enhancement in GSH and ajmalicine content under GA(3) foliar spray in C. roseus. These preliminary results suggest that, the application of GA(3) may be a useful tool to increase the antioxidant potential and alkaloid production in medicinal plants like C. roseus. 相似文献
36.
Immunoassay is a powerful tool for rapid detection of food borne pathogens in food safety monitoring. However, conventional immunoassay always suffers from low sensitivity when it employs enzyme-catalyzing chromogenic substrates to generate colored molecules as signal outputs. In the present study, we report a novel fluorescence immunoassay for the sensitive detection of E. coli O157:H7 through combination of the ultrahigh bioactivity of catalase to hydrogen peroxide (H2O2) and H2O2-sensitive mercaptopropionic acid modified CdTe QDs (MPA-QDs) as a signal transduction. Various parameters, including the concentrations of anti-E. coli O157:H7 polyclonal antibody and biotinylated monoclonal antibody, the amounts of H2O2 and streptavidin labeled catalase (CAT), the hydrolysis temperature and time of CAT to H2O2, as well as the incubation time between H2O2 and MPA-QDs, were systematically investigated and optimized. With optimal conditions, the catalase-mediated fluorescence quenching immunoassay exhibits an excellent sensitivity for E. coli O157:H7 with a detection limit of 5 × 102 CFU/mL, which was approximately 140 times lower than that of horseradish peroxidase-based colorimetric immunoassay. The reliability of the proposed method was further evaluated using E. coli O157:H7 spiked milk samples. The average recoveries of E. coli O157:H7 concentrations from 1.18 × 103 CFU/mL to 1.18 × 106 CFU/mL were in the range of 65.88%–105.6%. In brief, the proposed immunoassay offers a great potential for rapid and sensitive detection of other pathogens in food quality control. 相似文献
37.
微量热法研究过氧化氢酶反应 总被引:4,自引:1,他引:3
利用微量热法和热动力学方程研究了过氢化氢酶反应.该反应遵循Michaelis-Menten动力学,298.15K和pH7.0时,其米氏常数、酶转换数以及摩尔反应焓分别为2.36×10-2mol/L、1.20×104s-1和-83.67kJ·mol-1.过氧化氢酶反应后期对底物是一级反应,其总反应速度常数和一级速度常数分别为ko=6.31×105L·mol-1·s-1和k1=6.31×105/[Eo]s-1.该反应服从Ogura机理,其酶-底物三元复合物的分解速度常数为6.00×103s-1. 相似文献
38.
通过10—15个杂交组合的F1及其双亲的稻苗接稻瘟菌小种zb,并经发病鉴定和生化测定表明,F1苗期的抗瘟性比其双亲强,且F1的过氧化物酶和多酚氧化酶的活性含量均比其F1对照增加幅度大,相关极显著,经大田试验,结果相似,采用这些生化指标的新技术,作为预测高抗稻瘟种源,培育抗稻瘟高 相似文献
39.
40.
LIUJian-yu SUNBao-wei LIYuan-zong CHANGWen-bao 《高等学校化学研究》2003,19(3):335-339
Hemoglobin(Hb) was de-prosthetized, which was then reconstructed with the prosthetic groups with different central metal ions including Fe ( Ⅱ ), Co ( Ⅰ ) and Mn( Ⅰ ). The spectral properties along with the catalase and peroxidase activities of the reconstructed hemoglobin were compared with those of Hb and prosthetic groups with different ions. When the central ion is iron, the reconstituted Hb(rHb) has the highest catalase and peroxidase activities. Maybe it is the reason that iron is chosen as the central ion in the prosthetic groups of natural hemoproteins. Different from peroxidase activity, the catalase activity of hemin cannot be enhanced by the microenvironment of apoHb. This result shows that the structure of apoHb is more similar to that of aooHRP than that of apocatalase. 相似文献