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1.
Bovine liver catalase was encapsulated in an aqueous phase of the phospholipid vesicle (liposome) to improve the stability of its tetrameric structure and activity. The catalase-containing liposomes (CALs) prepared were 30, 50 and 100 nm in mean diameters (CAL 30, CAL 50 and CAL 100, respectively). The CAL 100 included the types I, II and III based on the amounts of catalase encapsulated. The CAL 30, CAL 50 and CAL 100-I contained one catalase molecule per liposome, and the CAL 100-II and CAL 100-III on average 5.2 and 17 molecules, respectively. The storage stability of catalase in either CAL system was significantly increased compared to that of free catalase at 4 °C in a buffer of pH 7.4. At 55 °C, free catalase was much more deactivated especially with decreasing its concentration predominantly due to enhanced dissociation of catalase into subunits while it was so done at excessively high enzyme concentration mainly due to enhanced formation of catalase intermolecular aggregates. Among the three types of CAL 100, the CAL 100-II showed the highest thermal stability, indicating that an excess amount of catalase in the CAL 100-III was also disadvantageous to maintain an active form of the catalase even in liposome. In the CAL 100-III, however, the stability of catalase was significantly improved compared to that of free catalase at the same concentration. The CAL thermal stability was little affected by the liposome size as observed in the CAL 30, CAL 50 and CAL 100-I. An intrinsic tryptophan fluorescence of the catalase recovered from the CAL 100-II thermally treated at 55 °C revealed that a partially denatured catalase molecule was stabilized through its hydrophobic interaction with liposome membrane. This interaction depressed not only dissociation of catalase into subunits but also formation of an inactive intermolecular aggregate between the catalase molecules in a liposome. Furthermore, either type of CAL 100 showed a higher stability than free catalase in the successive decompositions of 10 mM H 2O 2 at 25 °C mainly because the H 2O 2 concentration was kept low inside liposomes due to the permeation barrier of the lipid membrane to H 2O 2. 相似文献
2.
Whole cells of Bacillus halodurans LBK 261 were used as a source of catalase for degradation of hydrogen peroxide. The organism, B. halodurans grown at 55°C and pH 10, yielded a maximum catalase activity of 275 U g -1 (wet wt.) cells. The catalase in the whole cells was active over a broad range of pH with a maximum at pH 8-9. The enzyme was optimally active at 55°C, but had low stability above 40°C. The whole cell biocatalyst exhibited a Km of 6.6 mM for H 2O 2 and Vmax of 707 mM H 2O 2 min -1 g -1 wet wt. cells, and showed saturation kinetics at 50 mM H 2O 2. The cells were entrapped in calcium alginate and used for H 2O 2 degradation at pH 9 in batch and continuous mode. In the batch process, the immobilized preparation containing 1.5 g (wet wt.) cells could be recycled at least four times for complete degradation of the peroxide in 50 mL solution at 25°C. An excess of immobilized biocatalyst could be used in a continuous stirred tank reactor for an average of 9 days at temperatures upto 55°C, and in a packed bed reactor (PBR) for 5 days before the beads started to deform. 相似文献
3.
There is increasing evidence that hydrogen peroxide (H 2O 2) may act as a neuromodulator in the brain, as well as contributing to neurodegeneration in diseased states, such as Parkinson's disease. The ability to monitor changes in endogenous H 2O 2 in vivo with high temporal resolution is essential in order to further elucidate the roles of H 2O 2 in the central nervous system. Here, we describe the in vitro characterization of an implantable catalase-based H 2O 2 biosensor. The biosensor comprises two amperometric electrodes, one with catalase immobilized on the surface and one without enzyme (blank). The analytical signal is then the difference between the two electrodes. The H 2O 2 sensitivity of various designs was compared, and ranged from 0 to 56 ± 4 mA cm −2 M −1. The most successful design incorporated a Nafion ® layer followed by a poly- o-phenylenediamine (PPD) polymer layer. Catalase was adsorbed onto the PPD layer and then cross-linked with glutaraldehyde. The ability of the biosensors to exclude interference from ascorbic acid, and other interference species found in vivo, was also tested. A variety of the catalase-based biosensor designs described here show promise for in vivo monitoring of endogenous H 2O 2 in the brain. 相似文献
4.
β-Amyloid peptide (Aβ) 1–42, involved in the pathogenesis of Alzheimer’s disease, binds copper ions to form Aβ · Cu n complexes that are able to generate H 2O 2 in the presence of a reductant and O 2. The production of H 2O 2 can be stopped with chelators. More reactive than H 2O 2 itself, hydroxyl radicals HO (generated when a reduced redox active metal complex interacts with H 2O 2) are also probably involved in the oxidative stress that creates brain damage during the disease. We report in the present work a method to monitor the effect of chelating agents on the production of hydrogen peroxide by metallo-amyloid peptides. The addition of H 2O 2 associated to a pre-incubation step between ascorbate and Aβ · Cu n allows to study the formation of H 2O 2 but also, at the same time, its transformation by the copper complexes. Aβ · Cu n peptides produce but do not efficiently degrade H 2O 2. The reported analytic method, associated to precipitation experiments of copper-containing amyloid peptides, allows to study the inhibition of H 2O 2 production by chelators. The action of a ligand such as EDTA is probably due to the removal of the copper ions from Aβ · Cu n, whereas bidentate ligands such as 8-hydroxyquinolines probably act via the formation of ternary complexes with Aβ · Cu n. The redox activity of these bidentate ligands can be modulated by the incorporation or the modification of substituents on the quinoline heterocycle. 相似文献
5.
The formation and reactivity of ferryl haemoglobin (and myoglobin), which occurs on addition of H 2O 2, has been proposed as a mechanism contributing to oxidative stress associated with human diseases. However, relatively little is known of the reaction between hydrogen peroxide and human haemoglobin. We have studied the reaction between hydrogen peroxide and purified (catalase free) human metHbA. Addition of H 2O 2 resulted in production of both ferryl haem iron (detected by optical spectroscopy) and an associated protein radical (detected by EPR spectroscopy). Titrating metHbA with H 2O 2 showed that maximum ferryl levels could be obtained at a 1:1 stoichiometric ratio of haem to H 2O 2. No oxygen was evolved during the reaction, indicating that human metHbA does itself not possess catalatic activity. The protein radicals obtained in this reaction reached a steady state concentration, during hydrogen peroxide decomposition, but started to decay once the hydrogen peroxide had been completely exhausted. The presence of catalase, at concentrations around 10 fold lower than metHb, increased the apparent stoichiometry of the reaction to 1 mol metHb: ∼20 mol H 2O 2 and abolished the protein radical steady state. The biological implications for these results are discussed. 相似文献
6.
Heme catalases are considered to degrade two molecules of H 2O 2 to two molecules of H 2O and one molecule of O 2 employing the catalatic cycle. We here studied the catalytic behaviour of bovine liver catalase at low fluxes of H 2O 2 (relative to catalase concentration), adjusted by H 2O 2-generating systems. At a ratio of a H 2O 2 flux (given in μM/min - 1) to catalase concentration (given in μM) of 10 min - 1 and above, H 2O 2 degradation occurred via the catalatic cycle. At lower ratios, however, H 2O 2 degradation proceeded with increasingly diminished production of O 2. At a ratio of 1 min - 1, O 2 formation could no longer be observed, although the enzyme still degraded H 2O 2. These results strongly suggest that at low physiological H 2O 2 fluxes H 2O 2 is preferentially metabolised reductively to H 2O, without release of O 2. The pathways involved in the reductive metabolism of H 2O 2 are presumably those previously reported as inactivation and reactivation pathways. They start from compound I and are operative at low and high H 2O 2 fluxes but kinetically outcompete the reaction of compound I with H 2O 2 at low H 2O 2 production rates. In the absence of NADPH, the reducing equivalents for the reductive metabolism of H 2O 2 are most likely provided by the protein moiety of the enzyme. In the presence of NADPH, they are at least in part provided by the coenzyme. 相似文献
7.
[MnL](ClO 4) 2 (L = N, N′, N″-tris(2-hydroxypropyl)-1,4,7-triazacyclononane) has been tested for catalyzing sulfide oxidation. In the presence of this complex, ethyl phenyl sulfide, butyl sulfide and phenyl sulfide are completely oxidized to the corresponding sulfoxides and sulfones with H 2O 2 as the oxidant. 2-Chloroethyl phenyl sulfide oxidation yield 2-chloroethyl phenyl sulfone and phenyl vinyl sulfone. In ethyl phenyl sulfide oxidation, effects of complex and H 2O 2 concentration and temperature on the reaction rate have been discussed. Through controlling reaction conditions, ethyl phenyl sulfoxide and ethyl phenyl sulfone may be produced selectively. The UV–Vis and electron paramagnetic resonance (EPR) studies on catalyst solution indicate that metal centre of the complex is transformed from Mn(II) to Mn(IV) after the addition of H 2O 2. At 25 °C, rate constant for ethyl phenyl sulfide oxidation is 4.38 × 10 −3 min −1. 相似文献
8.
The effect of vitamin C (ascorbate) on oxidative DNA damage was examined by first incubating cells with dehydroascorbate, which boosts the intracellular concentration of ascorbate, and then exposing cells to H 2O 2. Oxidative DNA damage was estimated by the analysis of 5-hydroxy-2′-deoxycytidine (oh 5dCyd) and 8-oxo-7,8-dihydro-2′-deoxyguanosine (oxo 8dGuo). The presence of a high concentration of ascorbate (30 mM), compared to the absence of ascorbate in cells, when exposed to H 2O 2 (200 μM), resulted in a remarkable sensitization of oh 5dCyd from 2.7 ± 0.6 to 40.8 ± 6.1 lesions /10 6 dCyd (15-fold). In contrast, the level of oxo 8dGuo increased from 8.4 ± 0.4 to 12.1 ± 0.5 lesions/10 6 dGuo (50%). The formation of oh 5dCyd was also observed at lower concentrations of intracellular ascorbate and exogenous H 2O 2. Additional studies showed that replacement of H 2O 2 with tert-butyl hydroperoxide completely abolished damage, and that preincubation with iron and desferroxamine increased and decreased this damage, respectively. The latter studies suggest that a Fenton reaction is involved in the mechanism of damage. In conclusion, we report a novel model system in which ascorbate sensitizes H 2O 2-induced oxidative DNA damage in cells, leading to elevated levels of oh 5dCyd and oxo 8dGuo, with a strong bias toward the formation of oh 5dCyd. 相似文献
9.
The reaction of H 2[PtCl 6] · 6H 2O and (H 3O)[PtCl 5(H 2O)] · 2(18C6) · 6H 2O (18C6 = 18-crown-6) with 9-methylguanine (MeGua) proceeded with the protonation of MeGua forming 9-methylguaninium hexachloroplatinate(IV) dihydrate (MeGuaH) 2[PtCl 6] · 2H 2O (1).The same compound was obtained from the reaction of Na 2[PtCl 6] with (MeGuaH)Cl.On the other hand, the reaction of guanosine (Guo) with (H 3O)[PtCl 5(H 2O)] · 2(18C6) · 6H 2O in methanol at 60 °C proceeded with the cleavage of the glycosidic linkage and with ligand substitution to give a guaninium complex of platinum(IV), [PtCl 5(GuaH)] · 1.5(18C6) · H 2O (2).Within several weeks in aqueous solution a slow reduction took place yielding the analogous guaninium platinum(II) complex, [PtCl 3(GuaH)] · (18C6) · 2Me 2CO (3).H 2[PtCl 6] · 6H 2O and guanosine was found to react in water, yielding (GuoH) 2[PtCl 6] (4) and in ethanol at 50 °C, yielding [PtCl 5(GuoH)] · 3H 2O (5).Dissolution of complexes 2 and 5 in DMSO resulted in the substitution of the guaninium and guanosinium ligands, respectively, by DMSO forming [PtCl 5(DMSO)] −.Reactions of 1-methylcytosine (MeCyt) and cytidine (Cyd) with H 2[PtCl 6] · 6H 2O and(H 3O)[PtCl 5(H 2O)] · 2(18C6) · 6H 2O resulted in the formation of hexachloroplatinates with N3 protonated pyrimidine bases as cation (MeCytH) 2[PtCl 6] · 2H 2O (6) and (CydH) 2[PtCl 6] (7), respectively. Identities of all complexes were confirmed by 1H, 13C and 195Pt NMR spectroscopic investigations, revealing coordination of GuoH + in complex 5 through N7 whereas GuaH + in complex 3 may be coordinated through N7 or through N9. Solid state structure of hexachloroplatinate 1 exhibited base pairing of the cations yielding (MeGuaH +) 2, whereas in complex 6 non-base-paired MeCytH + cations were found. In both complexes, a network of hydrogen bonds including the water molecules was found. X-ray diffraction analysis of complex 3 exhibited a guaninium ligand that is coordinated through N9 to platinum and protonated at N1, N3 and N7. In the crystal, these NH groups form hydrogen bonds N–HO to oxygen atoms of crown ether molecules. 相似文献
10.
Trehalose is known to protect membranes and macromolecules. Its accumulation has been implicated in allowing plants to tolerate stress, including heat-shock. However, under heat-shock, it is not clear whether trehalose eliminates reactive oxygen species (ROS) directly or indirectly by protecting antioxidant enzymes. In this study, we initially examined the effects of trehalose on the activities of key antioxidant enzymes, including superoxide dismutases (SODs), ascorbate catalases (CATs), and ascorbate peroxidases (APX) from wheat ( Triticum aestivum L.), and then measured the ability of trehalose to scavenge hydrogen peroxide (H 2O 2) and superoxide anions (O 2−). Our results indicated that trehalose protected SOD activity slightly. However, it inhibited CAT and APX activities under heat stress, with a little protection of CAT activity (only about 7% promotion) at 22 °C. Moreover, trehalose scavenged H 2O 2 and O 2− greatly in a concentration-dependent manner, reaching the maximal scavenging H 2O 2 rate of 95% and O 2− rate of 78%, respectively, at 50 mM trehalose. These results suggest that trehalose plays a direct role in eliminating H 2O 2 and O 2− in wheat under heat stress. 相似文献
11.
1. Single reduced methyl viologen (MV .+) acts as an electron donor in a number of enzyme systems. The large changes in extinction coefficient upon oxidation (λ max 600 nm; MV .+, = 1.3 · 10 4 M −1 · cm −1; oxidised form of methyl viologen (MV 2+), = 0.0) make it ideally suited to kinetic studies of electron transfer reactions using stopped-flow and standard spectrophotometric techniques. 2. A convenient electrochemical preparation of large amounts of MV.+ has been developed. 3. A commercial stopped-flow apparatus was modified in order to obtain a high degree of anaerobicity. 4. The reaction of MV.+ with O2 produced H2O2 (k > 5 · 106 M−1 · s−1, pH 7.5, 25 °C). H2O2 subsequently reacted with excess MV.+ (k = 2.3 · 103 M−1 · s−1, pH 7.5, 25 °C) to produce water. The kinetics of this reaction were complex and have only been interpreted over a limited range of concentrations. 5. The results support the theory that the herbicidal action of methyl viologen (Paraquat, Gramoxone) is due to H2O2 (or radicals derived from H2O2) induced damage of plant cell membrane. 相似文献
12.
Two new multi-cobalt-containing polyoxotungstates K 4Na 6Co 2(H 2O) 12{Co(H 2O) 4[Co 2(H 2O) 10Co 4(H 2O) 2( B--SiW 9O 34) 2] 2} · 40H 2O (1) and K 10Na 2[Co 4(H 2O) 2(GeW 9O 34) 2] · 20H 2O (2) have been obtained by the routine synthetic reactions in aqueous solution. The polyoxoanion framework of 1 consists of two sandwich-type polyoxoanions [Co 4(H 2O) 2( B--SiW 9O 34) 2] 12− connected together by a [CoO 2(H 2O) 4] cluster to constitute the sandwich dimer, and then, four isolated Co(H 2O) 5 cations coordinate to the dimer through four μ2-O atoms. The polyoxoanion 2 is isomorphic to the sandwich-type polyoxoanion [Co 4(H 2O) 2( B--SiW 9O 34) 2] 12− in 1. The magnetic property of compound 1 has been studied by measuring its magnetic susceptibility in the temperature range 2.0–300.0 K, indicating the existence of intramolecular ferromagnetic Co–Co interactions, and, the electrochemical properties of 1 and 2 are detected in the pH 4 buffer solution. 相似文献
13.
This work presents a novel, miniature optical biosensor by immobilizing horseradish peroxidase (HRP) or the HRP/glucose oxidase (GOx) coupled enzyme pair on a CMOS photosensing chip with a detection area of 0.5 mm × 0.5 mm. A highly transparent TEOS/PDMS Ormosil is used to encapsulate and immobilize enzymes on the surface of the photosensor. Interestingly, HRP-catalyzed luminol luminescence can be detected in real time on optical H 2O 2 and glucose biosensors. The minimum reaction volume of the developed optical biosensors is 10 μL. Both optical H 2O 2 and glucose biosensors have an optimal operation temperature and pH of 20–25 °C and pH 8.4, respectively. The linear dynamic range of optical H 2O 2 and glucose biosensors is 0.05–20 mM H 2O 2 and 0.5–20 mM glucose, respectively. The miniature optical glucose biosensor also exhibits good reproducibility with a relative standard deviation of 4.3%. Additionally, ascorbic acid and uric acid, two major interfering substances in the serum during electrochemical analysis, cause only slight interference with the fabricated optical glucose biosensor. In conclusion, the CMOS-photodiode-based optical biosensors proposed herein have many advantages, such as a short detection time, a small sample volume requirement, high reproducibility and wide dynamic range. 相似文献
14.
The response characteristics of a new enzyme electrode for determining choline are reported. The enzyme electrode consists of a polyvinylferrocenium perchlorate coated Pt surface onto which the enzyme, choline oxidase, is attached. Choline oxidase catalyzes the oxidation of choline to betaine, producing H 2O 2. Current due to H 2O 2 oxidation catalyzed by polyvinylferrocenium centers was measured. The effects of choline concentration, the amount of enzyme immobilized and the operating pH and temperature on the response of the enzyme electrode were studied. The effects of interferents were also investigated. The response time was found to be 60–70 s and the upper limit of the linear working portion was found to be 1.2 mM choline concentration. The minimum substrate concentration that produced detectable current was 4.0×10 −6 M choline concentration. The steady-state current of this enzyme electrode was reproducible within ±4.6% of relative error. The apparent Michaelis–Menten constant ( KMapp) and the activation energy, Ea, of this immobilized enzyme system were found to be 2.32 mM and 38.91 kJ/mol, respectively. 相似文献
15.
The individual and interactive effects of pH, temperature and substrate concentration on the biohydrogen production from sucrose by mixed anaerobic cultures were investigated in this study. A central composite design and response surface methodology (RSM) were employed in planning the experiments, in order to determine the optimum conditions for biohydrogen production. Experimental results show that pH, temperature and substrate concentration all had a significant influence on specific hydrogen production potential ( Ps) and the maximum hydrogen production rate ( Rmax) individually. Temperature and sucrose concentration, pH and temperature were interdependent or there was a significant interaction on Ps and Rmax. Substrate concentration and pH were slightly interdependent, or their interactive effect on Ps and Rmax was not significant. A maximum Ps of 252 mL H 2/g sucrose was estimated under the optimum conditions of pH 5.5, temperature 34.8 °C and sucrose concentration of 24.8 g/L, while a maximum Rmax of 1511 mL H 2/h was calculated under the optimum conditions of pH 5.5, temperature 35.5 °C and sucrose concentration of 25.4 g/L. The experiment results show that the RSM with the central composite design was useful for optimizing the biohydrogen-producing process. 相似文献
16.
The effect of a range of iron chelates on the cytotoxicity of H 2O 2 was studied on a mammalian epithelial cell line. Iron complexes which were internalised enhanced the cytotoxicity of H 2O 2 measured by delayed thymidine incorporation. Iron complexed to 8-hydroxyquinoline (Fe/8-HQ) potentiated the cytotoxicity of 50 µM by 38% and Fe/dextran by 23%. Pre-exposure of cells to Fe/dextran at 4°C did not result in any potentiation of H 2O 2-induced cytotoxicity which we ascribe to failure of the Fe/dextran to be endocytosed at low temperature. Iron complexes which are slowly taken up or remain extracellular protected the cells from H 2O 2-induced cytotoxicity. Thus, Fe/EDTA inhibited the cytotoxicity of 50 µM H 2O 2 by 33%; Fe/ADP by 80% and Fe/ATP by 88%, suggesting mutual extracellular detoxification. 相似文献
17.
In this work we present the synthesis, structural and spectroscopic characterisation of a series of cobalt(II) and zinc(II) coordination compounds with benzimidazole (bz) and its 2-benzimidazole derivatives: 2-aminobenzimidazole (2ab), albendazole (abz) and tris(2-benzimidazolylmethyl)amine (ntb). The compounds were evaluated for their in vitro antimicrobial activity against Staphylococcus aureus, Micrococcus luteus, Salmonella typhi, Pseudomonas aeruginosa, Escherichia coli and Proteus vulgaris. Their cytotoxic activity was also evaluated using human cancer lines, HeLa, HCT-15 and SKLU-1. The halide tetrahedral compounds [Co(bz) 2Br 2] 3, [Zn(2ab) 2Cl 2] · 0.5H 2O 11, [Co(abz)Cl 2(H 2O)] · 3H 2O 14, [Co(abz)Br 2(H 2O)] 15, [Zn(abz)Cl 2(H 2O)] · 3H 2O 17 and [Zn(abz)Br 2(H 2O)] · H 2O 18 displayed similar minimal inhibition concentration (MIC) values against Micrococcus luteus and Escherichia coli, comparable to those of amoxicillin and chloramphenicol. Additionally, 11 showed a wide range of activity towards Gram(+) and Gram(−) microorganisms. The tetradentate ntb and its trigonal bipyramidal cobalt(II) and zinc(II) compounds were active, regardless of the anion present in the complex. Compound [Co(abz)Cl 2(H 2O)] · 3H 2O 14 showed promising activity in HeLa cells, while [Co(ntb)Br]Br · H 2O 21 inhibited Hela and HCT-15 cell lines. 相似文献
18.
Manganese peroxidases (MnP) from Phanerochaete chrysosporium and Bjerkandera sp. BOS55 were immobilised in glutaraldehyde–agarose gels. Four different strategies were considered concerning the activation of the support (low or high density) and the ionic strength (low or high). In terms of immobilisation rate and yield, better results were obtained when low ionic strength conditions and high density activated support (75 μEq/ml) were used. Immobilisation proceeds initially with an ionic adsorption which facilitates the further covalent attachment of the enzyme to the support. An almost complete immobilisation has been attained in a very short period (0.5–2 h). Immobilisation maintained a high percentage of MnP activity for long periods of time (activity levels of 50–60% after more than 1 year at room temperature storage). Other desirable effects such as increased thermostability at 50–60 °C for MnP from Bjerkandera and higher resistance to high H 2O 2 concentrations for MnP for P. chrysosporium were also obtained. This latter is quite an interesting feature because it avoids the inactivation of the enzyme in the presence of an unbalanced concentration of H 2O 2. The improved characteristics of the immobilised MnP make its application in several fields such as the enzymatic oxidation of hardly degradable compounds more feasible. 相似文献
19.
We had earlier shown that higher concentration of hydrogen peroxide (H 2O 2) induced p53-dependent apoptosis in glioma cell line with wild type p53 but had minimal effect on cells with mutated p53. Here we show a potentiating effect of hydroxylamine (HA), an inhibitor of catalase, on a nontoxic dose of H 2O 2 in glioma cells. HA sensitized both p53 wild type and mutated glioma cells to 0.25 mM H 2O 2. Potentiating effect of HA was independent of p53. Higher levels of reactive oxygen species (ROS) generation were observed in cells treated with HA+H 2O 2 as compared to cells treated with each component alone in both the cell lines. Dimethyl sulfoxide (DMSO) protected cells. Cytosolic cytochrome c and activated caspase 3 were detected at 4 h. The results suggest that higher levels of intracellular ROS, generated by HA+H 2O 2 act as a molecular switch in activating a rapidly acting p53-independent mitochondrial apoptotic pathway. 相似文献
20.
Three-dimensionally (3D) ordered macroporous active carbon has been fabricated and used as electrode substrate for the direct electrochemistry of horse heart cytochrome c (Cyt c). The Cyt c immobilized on the surface of the ordered macroporous active carbon shows a pair of well-defined and nearly reversible redox waves at the formal potential of −0.033 V in pH 6.8 phosphate buffer solution. The interaction between Cyt c and the 3D macroporous active carbon makes the formal potential shift negatively compared to that of Cyt c in solution. Spectrophotometric and electrochemical methods have been used to investigate the interaction between Cyt c and the porous active carbon. The immobilized Cyt c maintains its biological activity, and shows a surface controlled electrode process with the electron-transfer rate constant ( ks) of 17.6 s −1 and the charge-transfer coefficient ( a) of 0.52, and displays the features of a peroxidase in the electrocatalytic reduction of hydrogen peroxide (H 2O 2). A potential application of the Cyt c-immobilized porous carbon electrode as a biosensor to monitor H 2O 2 has been investigated. The steady-state current response increases linearly with H 2O 2 concentration from 2.0 × 10 −5 to 2.4 × 10 −4 mol l −1. The detection limit (3 σ) for determination of H 2O 2 has been found to be 1.46 × 10 −5 mol l −1. 相似文献
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