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1.
The coupling reaction of 4-aminoantipyrine (4-AAP) with phenol using the superoxide anion radical (
) as oxidizing agent under the catalysis of horseradish peroxidase (HRP) was studied. Based on the reaction,
produced by irradiating vitamin B2 (VB2) was spectrophotometrically determined at 510 nm. Under the optimum experimental conditions, the relationship between A
510 and
concentration was linear in the range 9.14×10–6–1.2×10–4 mol L–1. The detection limit was determined to be 1.37×10–6 mol L–1. A possible reaction mechanism was discussed. The effect of interferences and surfactants on the determination of
was also investigated. The proposed method was applied to determine superoxide dismutase activity in garlic, scallion, and onion with satisfactory results. 相似文献
2.
A new kind of near-infrared fluorescence agent, tricarbochlorocyanine dye (Cy.7.Cl), had been synthesized in house and used for near-infrared spectrofluorimetric determination of hydrogen peroxide (H2O2) by flow injection analysis (FIA) for the first time. The oxidation reaction of Cy.7.Cl with H2O2 occurred under the catalysis of horseradish peroxidase (HRP) and it was studied in detail. The possible reaction mechanism was discussed. Under optimal experimental conditions, fluorescence from Cy.7.Cl displayed excitation and emission maxima (ex/em) at 780 and 800 nm, respectively. The two linear working ranges were 1.86 × 10−7 to 4.11 × 10−7 mol L−1 and 4.11 × 10−7 to 7.19 × 10−6 mol L−1, respectively. The detection limit was 5.58 × 10−8 mol L−1 of H2O2. The effect of interferences was studied. The proposed method was successfully applied to the determination of hydrogen peroxide in rainwater, serum and plant samples. 相似文献
3.
Bo Tang Yan Wang Ying Sun Han Xi Shen 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(1):141-148
The oxidation reaction of HNSH with H2O2 under the catalysis of HRP was studied in detail. The possible reaction mechanism was discussed. Under optimum experimental conditions, the oxidized product of HNSH had excitation and emission maxima at 296 and 414 nm, respectively. A study to prove the existence of -O-O-H in polyethylene glycols was carried out. The proposed method was successfully applied to the determination of -O-O-H in polyethylene glycols. 相似文献
4.
Tang B Wang Y 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(12):2867-2874
2-Hydroxy-1-naphthaldehyde thiosemicarbazon (HNT) had been synthesized and used as a new kind of substrate for horseradish peroxidase (HRP) in spectrofluorimetric determination of hydrogen peroxide (H(2)O(2)). The oxidation reaction of HNT with H(2)O(2) under the catalysis of HRP was studied in detail. The possible reaction mechanism was discussed. Under optimum experimental conditions, the oxidized product of HNT had excitation and emission maxima at 260 and 450 nm, respectively. The linear range of this method was 1.30 x 10(-9)-1.25 x 10(-5) mol l(-1) with a detection limit of 3.89 x 10(-10) mol l(-1). The effect of interferences, surfactants and organic solvents on the determination of H(2)O(2) had been investigated. A study to prove the existence of -O-O-H in PEGs was carried out. The proposed method was successfully applied to the determination of -O-O-H in polyethylene glycols. 相似文献
5.
The use of 3-indoxyl phosphate (3-IP) as an electrochemical substrate for ELISAs with voltammetric detection was investigated. Indirect measurements of alkaline phosphatase (AP) and horseradish peroxidase (HRP) activity in solution were carried out. Picomolar levels of both enzymes can be detected, which enables the design of electrochemical immunoassays using this substrate. The enzymatic turnover of the substrate gives indigo blue, insoluble in aqueous solutions. This product is easily converted into its soluble parent compound, indigo carmine (IC), by addition of fuming sulphuric acid to the reaction media. IC shows a reversible voltammetric peak at the formal potential of −0.15 V (versus Ag pseudo-reference electrode) when a screen-printed carbon electrode (SPCE) is used. The peak current of this process constitutes the analytical signal. Using this approach an ELISA assay to quantify pneumolysin (PLY, a toxin related to respiratory infections) was carried out using AP or HRP as enzymatic label. Calibration plots obtained are reported. 3-IP is demonstrated to be the first suitable substrate for the two most common enzyme labels used in immunoassays. 相似文献
6.
Dibyendu Das 《Tetrahedron letters》2007,48(32):5635-5639
The ionic liquid (IL), tetrakis (2-hydroxyethyl) ammonium triflouromethanesulfonate is rationally designed for horseradish peroxidase (HRP) on the basis of its stability and activity in the presence of an excipient, tris(hydroxymethyl)aminoethane (TRIS) in different ILs. The activity of HRP in this tailor made IL is at least 30-240-fold higher than that in conventional ILs. Also, the activity is more than 10 times greater than that in methanol, a common organic solvent used for HRP. 相似文献
7.
Zhu X Gao X Liu Q Lin Z Qiu B Chen G 《Chemical communications (Cambridge, England)》2011,47(26):7437-7439
A novel nucleic acid hairpin structure composed of Pb(2+)-dependent DNAzyme and HRP-mimicking DNAzyme was developed. This hairpin structure can be used as a sensor for the detection of Pb(2+) based on colorimetry. 相似文献
8.
Dezhan Chen Qingli Wang Honghong Zhang Shizhen Mi Juliang Wang Qiang Zeng Guiqiu Zhang 《International journal of quantum chemistry》2010,110(7):1394-1401
The disproportionation of superoxide radical anions catalyzed by copper‐zinc superoxide dismutase was investigated in detail using density functional theory. The structures of each stationary point and the transition states were located so that the reaction pathways were determined. The results indicate that the reactions proceed by two steps both for the oxidized process of superoxide radical anion and the reduced one. The rate for the determining step of the reaction (2) is in very good agreement with the experimental value. The solvation effect on the reaction was also discussed. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献
9.
Kutala VK Villamena FA Ilangovan G Maspoch D Roques N Veciana J Rovira C Kuppusamy P 《The journal of physical chemistry. B》2008,112(1):158-167
The reaction of superoxide radical with a tricarboxylate derivative of perchlorotriphenylmethyl radical (PTM-TC) is studied. PTM-TC is a stable ("inert") free radical, which gives a single sharp electron paramagnetic resonance (EPR) peak in aqueous solutions. PTM-TC also gives a characteristic optical absorption at 380 nm. Superoxide, on reaction with PTM-TC, induced a decrease in the intensity of the EPR signal and optical absorption of PTM-TC at 380 nm. The signal loss was specific to superoxide and linearly dependent on the superoxide flux in the system. Competitive kinetics experiments revealed that PTM-TC reacts with superoxide with an apparent second-order rate constant of 8.3x10(8) M(-1) s(-1). Electrochemical and mass spectrometric analyses of the reaction suggested the formation of perchlorotriphenylmethane and molecular oxygen as products. The high sensitivity of detection of PTM-TC combined with the high rate constant of the reaction of superoxide with PTM-TC may offer a potential opportunity for measurement of superoxide in biological systems. In conclusion, the PTM-TC molecule has high sensitivity and specificity for superoxide radicals and thus may enable quantitative detection of superoxide generation in biological systems using EPR and/or spectrophotometric methods. 相似文献
10.
A new capillary electrophoresis method was developed to study the synergistic effect of superoxide dismutase and jujuboside A or B on scavenging superoxide anion radical in serum matrix respectively, in which superoxide anion radical was generated from pyrogallol autoxidation. The electrophoresis conditions, and the factors affecting the productive rate of purpurogallin, such as pyrogallol autoxidation product and the activity of superoxide dismutase, were optimized. Under optimal conditions, the content of superoxide dismutase in Gibco newborn calf serum was 7.06 mg/L, RSD was 2.01% and the average recovery was 98.4%. The values of IC50 for jujuboside A and B in the serum matrix were 157.67 and 31.60 mg/L respectively, and they both had synergy on scavenging superoxide anion radical with superoxide dismutase, but there was no the dose‐dependency on this synergy. 相似文献
11.
de Visser SP Shaik S Sharma PK Kumar D Thiel W 《Journal of the American Chemical Society》2003,125(51):15779-15788
The active site of HRP Compound I (Cpd I) is modeled using hybrid density functional theory (UB3LYP). The effects of neighboring amino acids and of environmental polarity are included. The low-lying states have porphyrin radical cationic species (Por(*)(+)). However, since the Por(*)(+) species is a very good electron acceptor, other species, which can be either the ligand or side chain amino acid residues, may participate in electron donation to the Por(*)(+) moiety, thereby making Cpd I behave like a chemical chameleon. Thus, this behavior that was noted before for Cpd I of P450 is apparently much more wide ranging than initially appreciated. Since chemical chameleonic behavior property was found to be expressed not only in the properties of Cpd I itself, but also in its reactivity, the roots of this phenomenon are generalized. A comparative discussion of Cpd I species follows for the enzymes HRP, CcP, APX, CAT (catalase), and P450. 相似文献
12.
Durand G Choteau F Pucci B Villamena FA 《The journal of physical chemistry. A》2008,112(48):12498-12509
Nitrones have exhibited pharmacological activity against radical-mediated pathophysiological conditions and as analytical reagents for the identification of transient radical species by electron paramagnetic resonance (EPR) spectroscopy. In this work, competitive spin trapping, stopped-flow kinetics, and density functional theory (DFT) were employed to assess and predict the reactivity of O(2)(*-) and HO(2)(*) with various para-substituted alpha-phenyl-N-tert-butylnitrone (PBN) spin traps. Rate constants of O(2)(*-) trapping by nitrones were determined using competitive UV-vis stopped-flow method with phenol red (PR) as probe, while HO(2)(*) trapping rate constants were calculated using competition kinetics with 5,5-dimethylpyrroline N-oxide (DMPO) by employing EPR spectroscopy. The effects of the para substitution on the charge density of the nitronyl-carbon and on the free energies of nitrone reactivity with O(2)(*-) and HO(2)(*) were computationally rationalized at the PCM/B3LYP/6-31+G(d,p)//B3LYP/6-31G(d) level of theory. Theoretical and experimental data show that the rate of O(2)(*-) addition to PBN derivatives is not affected by the polar effect of the substituents. However, the reactivity of HO(2)(*) follows the Hammett equation and is increased as the substituent becomes more electron withdrawing. This supports the conclusion that the nature of HO(2)(*) addition to PBN derivatives is electrophilic, while the addition of O(2)(*-) to PBN-type compounds is only weakly electrophilic. 相似文献
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15.
Catalytic action of Mn‐superoxide dismutase in scavenging superoxide radical anion by double hydrogen abstraction from dihydrolipoic acid: A theoretical study
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The mechanism of scavenging superoxide radical anion ( ) by dihydrolipoic acid (diLA) in absence and presence of the enzyme Manganese‐superoxide dismutase (Mn‐SOD) has been investigated using density functional theory. Mn‐SOD was modelled by a complex of a manganese cation (Mn2+) bonded to three similar molecules having a histidine ring each and a water molecule. It has been shown that the scavenging mechanism involves double hydrogen abstraction by from different pairs of neighboring sites of diLA. It has been found that diLA alone cannot scavenge superoxide radical anions efficiently as the barrier energies involved in the reactions are very high. However, in presence of Mn‐SOD, owing to its catalytic action, the corresponding reactions become barrierless due to which superoxide radical anions would be scavenged highly efficiently. H2O2 formed from superoxide radical anion due to double hydrogen abstraction from diLA is scavenged by diLA alone barrierlessly without involving Mn‐SOD or any other catalyst. 相似文献
16.
Novel iron phosphates microflowers which show SOD-like and peroxidase-like mimic activities were prepared, suggesting potential applications as a biocatalyst and a biosensor for H(2)O(2). 相似文献
17.
以玻碳电极为工作电极研究了邻联甲苯胺(OT)为底物微分脉冲伏安法测定辣根过氧化物酶(HRP)及其标记物的方法。HRP能够催化H2O2氧化OT,其反应产物在玻碳电极上-0.58V(vs.Ag/AgCl)左右被还原产生一个灵敏的还原峰,还原峰电流随着酶浓度的增大而增大,借助此还原电流可以测定HRP,并进而可用于以HRP为标记物的酶免疫分析。对酶催化反应条件和酶催化反应产物的测定条件进行了详细的研究,在最佳实验条件下测定游离HRP的线性范围是2.0×10-9~4.0×10-8g/mL,检出限为1.6×10-9g/mL;测定游离的酶标记物(IgG HRP),稀释范围为1∶2000~1∶400000,最大稀释比为1∶400000。 相似文献
18.
As a chemiluminescent chemosensor that emits yellow light on reacting with a superoxide radical anion (O2−) and has a lipophilic character, a 6-phenylimidazo[1,2-a]pyrazin-3(7H)-one derivative possessing a boradiazaindacene (BODIPY) at the para position of 6-phenyl (1) was synthesized. The lipophilicity of 1 was investigated by reversed-phase liquid chromatography, and its log Pow value was found to be 3.57. This value was much higher than that of 2-methyl-6-(4-methoxypheyl)imidazo[1,2-a]pyrazin-3(7H)-one (MCLA, log Pow=1.19) and 6-[4-[2-{N′-(5-fluoresceinyl)thioureido}ethoxy]phenyl]-2-methylimidazo[1,2-a]pyrazin-3(7H)-one (FCLA, log Pow=−0.08), and it was comparable to that of benzenoid hydrocarbons. The O2−-induced chemiluminescence of 1 was investigated using the hypoxanthine/xanthine oxidase system as the source of O2−, and as a result, yellow emission was observed. The maximum wavelength was observed at 542 nm, and it was longer than that of FCLA. 相似文献
19.
Patel RN Singh N Gundla VL Chauhan UK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,66(3):726-731
A series of ternary copper(II) complexes containing same coordination sphere but difference in the counter ions, viz., [Cu(PMDT)(OAc)]PF(6)(1); [Cu(PMDT)(OAc)]ClO(4)(2); [Cu(PMDT)(OAc)]BF(4)(3) and [Cu(PMDT)(OAc)]BPh(4)(4) where PMDT=N,N,N',N',N'-pentamethyldiethylenetriamine, OAc=Acetate ion were synthesized and characterized by means of spectroscopic, magnetic and cyclic voltammetric measurements. In frozen solution e.p.r. spectra, an interesting relation g|| >g(perpendicular) has been observed which is atypical of the axially symmetric d(9) Cu(II) (S(Cu)=1/2) having an unpaired electron in a d (x2-y2) orbital. Single crystal X-ray analysis of (1) has revealed the presence of distorted square planar geometry. The influence of the counter ion on the complexes has been examined by performing some biological experiments like superoxide dismutase and anti-microbial activity. 相似文献
20.
Cyclic voltammetry was used to explore the interaction of (ferrocenylmethylamino) benzonitrile (FMAB) with superoxide anion radical (\({\text{O}}_{2}^{. - }\)), electrochemically generated by the reduction in commercial molecular oxygen in acetonitrile. The difference in the electrochemical behavior of \({\text{O}}_{2}^{. - }\) in the absence and presence of FMAB, including shifts in peak potential and decrease in anodic peak current, was successfully investigated for the determination of interaction parameters such as the binding constant, ratio of binding constants, binding free energy and mode of interaction. The anodic peak potential shifts and the magnitude of binding free energy ΔG suggest the electrostatic interaction of \({\text{O}}_{2}^{. - }\) with FMAB as the dominant mode, whereas the negative sign of ΔG indicates the spontaneity of the interaction. The antioxidant activity of FMAB derivatives was also evaluated using spectrophotometrical and electrochemical techniques. The spectrophotometrical assays were carried out using 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH), while the electrochemical assays were determined by measuring the oxidation peak current of \({\text{O}}_{2}^{. - }\). The activity was found to be highest for 3FMAB in both DPPH and \({\text{O}}_{2}^{. - }\) radicals scavenging methods (0.0183) and (0.0090 mg/mL), respectively, which is equal to half the antioxidant activity of standard antioxidant ascorbic acid (0.0117) and (0.0041 mg/mL). 相似文献