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1.
A pyrimethanil-imprinted polymer (P1) was prepared by iniferter-mediated photografting a mixture of methacrylic acid and ethylene dimethacrylate onto homemade near-monodispersed chloromethylated polydivinylbenzene beads. The chromatographic behaviour of a column packed with these imprinted beads was compared with another column packed with irregular particles obtained by grinding a bulk pyrimethanil-imprinted polymer (P2). The comparison was made using the kinetic model of non-linear chromatography, studying the elution of the template and of two related substances, cyprodinil and mepanipyrim. Extension of the region of linearity, capacity factors for the template and the related substances, column selectivity, binding site heterogeneity, apparent affinity constant (K) and lumped kinetic association (ka) and dissociation rate constant (kd) were studied during a large interval of solute concentration, ranging between 1 and 2000 μg/ml. From the experimental results obtained, in the linearity region of solute concentration column selectivity and binding site heterogeneity remained essentially the same for the two columns, while column capacity (at 20 μg/ml, P1 = 23.1, P2 = 11.5), K (at 20 μg/ml, P1 = 8.3 × 106 M−1, P2 = 2.5 × 106 M−1) and ka (at 20 μg/ml, P1 = 3.5 μM−1 s−1, P2 = 0.47 μM−1 s−1) significantly increased and kd (at 20 μg/ml, P1 = 0.42 s−1, P2 = 0.67 s−1) decreased for the column packed with the imprinted beads. These results are consistent with an influence of the polymerisation method on the morphology of the resulting polymer and not on the molecular recognition properties due to the molecular imprinting process.  相似文献   

2.
A novel binding phase was developed for use in diffusive gradients in thin-film (DGT) sampling for Cu(II) by employing methylthymol blue as a chelating and chromogenic agent. Methylthymol blue was adsorbed onto beads of Dowex 1 × 8 resin (200-400 mesh) and the resin beads were then immobilised onto an adhesive disc. Analysis of exposed binding discs by either UV-vis spectrophotometry or computer imaging densitometry provided robust quantification of adsorbed Cu(II) in the 0.2-1 μg cm−2 range, allowing detection at μg L−1 concentrations in the test solution (ca. 17 μg L−1 for a 24 h deployment), and in good agreement with established DGT theory. The method was shown to be a potential replacement for binding phases based on Chelex 100 where a colorimetric response to a specific metal is desired.  相似文献   

3.
The diffusion-controlled rate constants, kd, of various quenching reactions, [Ru(L)3]2+∗ (L = bpy, phen and 4,7-(CH3)2phen) + [Fe(CN)6]3−, were measured through fluorescence measurements. From them, the effective values of viscosity coefficients for several methanol + water mixtures were calculated. These coefficients were checked through calculations of the rate constants of the reaction [IrCl6]2− + [Ru(bpy)3]2+∗, which were also obtained by fluorescence quenching measurements. The agreement between the two sets of data (experimental and predicted) is excellent. Besides, the trends of association, kd, and dissociation, kd, rate constants for 2+/3−, 2+/2− and 2+/2+ reactions in methanol-water mixtures are discussed. The use of effective diffusion coefficients for estimating kd and kd allowed us to obtain the intrinsic electron transfer rate constant, ket, for the activation-diffusion-controlled process between [Ru(bpy)3]2+∗ and [Co(NH3)5Cl]2+ complexes from the observed (quenching) rate constant. The influence of methanol-water mixtures on ket was rationalized by using the Marcus electron-transfer treatment.  相似文献   

4.
The diffusive gradients in thin films technique (DGT) was used for uranium measurements in water. DGT devices with Dowex resin binding phase (Dow DGT) were tested in synthetic river water, which gave 84% response to total uranium concentration. The devices were also deployed in natural river water and compared to devices with other types of binding phases, Chelex 100 resin beads imbedded in polyacrylamide hydrogel (Chelex DGT) and DE 81 anion exchange membrane (DE DGT), deployed in the same location at the same time. The measurement by Dow DGT was the lowest among the different types of the DGT devices, 45% of total uranium, while measurement by DE DGT was the highest, 98% of total uranium. The results achieved by the three types of DGT devices were explained by three DGT working mechanisms, equilibrium between complexes of resin/uranyl carbonates and complexes of resin/competitive ligands in water, effective reduction of uranyl carbonate concentration by the binding phase and dissociation of UO2(CO3)22− and UO2(CO3)34− within the diffusive layer in a DGT device. It is hoped that by deploying the DGT devices with different binding phases in natural waters, additional information on uranium speciation could be obtained.  相似文献   

5.
The diffusive gradients in thin films (DGT) technique, utilizing resin gel with ion-exchange resin Duolite GT73 and new ion-exchange resin Ambersep GT74, was investigated for the accumulation of four mercury species (Hg2+, CH3Hg+, C2H5Hg+, C6H5Hg+). The diffusion coefficients of mercury species in agarose gel calculated on the basis of Fick’s Law were mercury species-specific. The diffusion coefficients of Hg2+ and CH3Hg+ at 25 °C (9.07 ± 0.23 × 10−6 cm2 s−1 and 9.06 ± 0.30 × 10−6 cm2 s−1, respectively) were very similar, but the diffusion coefficients of C2H5Hg+ (6.87 ± 0.23 × 10−6 cm2 s−1) and C6H5Hg+ (3.86 ± 0.19 × 10−6 cm2 s−1) were significantly lower. Influence of experimental conditions (pH, selected cations, chlorides and humic substance) on mercury species accumulation by DGT was studied. The DGT technique was applied to river water spiked with mercury species.  相似文献   

6.
In this article, we present a systematic study on IgG and Fab fragment of anti-IgG molecules using fluorescence auto- and cross-correlation spectroscopy to investigate their diffusion characteristics, binding kinetics, and the effect of small organic molecule, urea on their binding. Through our analysis, we found that the diffusion coefficient for IgG and Fab fragment of anti-IgG molecules were 37 ± 2 μm2 s−1 and 56 ± 2 μm2 s−1, respectively. From the binding kinetics study, the respective forward (ka) and backward (kd) reaction rates were (5.25 ± 0.25) × 106 M−1 s−1 and 0.08 ± 0.005 s−1, respectively and the corresponding dissociation binding constant (KD) was 15 ± 2 nM. We also found that urea inhibits the binding of these molecules at 4 M concentration due to denaturation.  相似文献   

7.
The kinetics of oxidative addition of CH3I to [Rh(FcCOCHCOCF3)(CO)(PPh3)], where Fc = ferrocenyl and (FcCOCHCOCF3) = fctfa = ferrocenoylacetonato, have been studied utilizing UV/Vis, IR, 1H and 31P NMR techniques. Three definite sets of reactions involving isomers of at least two distinctly different classes of RhIII-alkyl and two different classes of RhIII-acyl species were observed. Rate constants for this reaction in CHCl3 at 25 °C, applicable to the reaction sequence below, were determined as k1 = 0.00611(1) dm3 mol−1 s−1, k−1 = 0.0005(1) s−1, k3 = 0.00017(2) s−1 and k4 = 0.0000044(1) s−1 while k−3 ? k3 and k−4 ? k4 but both ≠0. The indeterminable equilibrium K2 was fast enough to be maintained during RhI depletion in the first set of reactions and during the RhIIIalkyl2 formation in the second set of reactions. From a 1H and 31P NMR study in CDCl3, Kc1 was found to be 0.68, Kc2 = 2.57, Kc3 = 1.00, Kc4 = 4.56 and Kc5 = 1.65.  相似文献   

8.
Fluoroheterocyclic aldoximes were screened as therapeutic agents for the treatment of anticholinesterase poisoning. 2-Fluoropyridine-3- and -6-aldoxime, and 3-fluoropyridine-2- and -4-aldoxime, were synthesised. Attempts to obtain 3,5,6-trifluoropyridine-2,4-bis(aldoxime) and -2-aldoxime, however, proved unsuccessful. Pentafluorobenzaldoxime was prepared by oximation of pentafluorobenzaldehyde. Acid dissociation constants (pKa) and second-order rate constants (kox−) of the fluorinated pyridinealdoximes towards sarin were measured. 2,3,5,6-Tetrafluoropyridine-4-aldoxime had the best profile: its kox− approached that of the therapeutic oxime P2S (310 vs. 120 l mol−1 min−1), but its higher pKa (9.1 vs. 7.8) fell short of the target figure of 8 required for reactivation of inhibited acetylcholinesterase in vivo. N-alkylation of the fluorinated pyridine-aldoximes may reduce their pKa nearer to 8 and enhance their therapeutic potential.  相似文献   

9.
A series of experiments were undertaken to investigate the effect of ionic strength and the concentration of free sodium ions in the resin gel on the performance of the diffusive gradients in thin films (DGT) technique. When the free sodium ion concentration in the resin gel was estimated by the time-dependent release into solution, it agreed with a previous estimate. However, equilibration with different volumes of water gave a higher value, suggesting that inherent averaging in the time-dependent release method underestimates the free concentration. DGT measurements of Cu and Cd were made over a wide range of ionic strengths (from 3 μmol l−1 to 0.8 mol l−1). For all the ionic strengths above 100 μmol l−1 there was no significant difference between measurements made by DGT and measurements made directly on the solution using atomic absorption spectroscopy. Below 100 μmol l−1 results were erratic. They did not comply with a theory that predicts high results for DGT based on enhancement of the diffusion coefficient of trace metal cations by counter diffusion of sodium ions. When Cd in solutions with a range of ionic strengths was measured by DGT there was no difference whether the resin gels were in Na or Ca form. Rather than counter diffusion of Na ions, it is suggested that the spurious behaviour at low ionic strength is due to interactions of the trace metals with the diffusion gel when there are insufficient excess cations present.  相似文献   

10.
The kinetics of the process [Pt(SNS)(R-py)]2+ + Cl → [Pt(SNS)Cl]+ + R-py {SNS = 2,6-bis(methylsulfanylmethyl)pyridine; R-py = meta- or para-substituted pyridines covering a wide range of basicity} were studied in methanol at 25 °C. The reactions obey the usual two-term rate law observed in the substitution reactions of square-planar d8 complexes. The plots of log k2 {k2 = second-order rate constants} against the pKa of the heterocycles conjugate acids highlighted a different sensitivity of the two groups of N-donors to changes in basicity, thepara-substituted pyridines (4R-py) showing a weaker dependence on pKa than the meta-substituted (3R-py). The results have been explained on the basis of a π-acidity difference between 3R-py and 4R-py which influences the reaction ground state.  相似文献   

11.
Hongtao Fan  Weijia Li  Shuang Jin 《Talanta》2009,79(5):1228-35
An aqueous solution containing sodium polyacrylate (PA, 0.0030 M) was used in diffusive gradients in thin-films technique (DGT) to measure DGT-labile Cu2+ and Cd2+ concentrations. The DGT devices (PA DGT) were validated in four types of solutions, including synthetic river waters containing metal ions with or without complexing EDTA, natural river water (Hun River, Shenyang, China) spiked with Cu2+ and Cd2+, and an industrial wastewater (Shenyang, China). Results showed that only free metal ions were measured by PA DGT, recovery = 98.79% for Cu2+ and recovery = 97.80% for Cd2+ in solutions containing only free metal ions, recovery = 51.02% for Cu2+ and recovery = 51.92% for Cd2+ in solution with metal/EDTA molar ratio of 2:1 and recovery = 0 in solutions with metal/EDTA molar ratio of 1:1 and 1:2. These indicated that the complexes of Cu-EDTA and Cd-EDTA were DGT-inert or not DGT-labile. The DGT performance in spiked river water (recovery = 8.47% for Cu2+ and recovery = 27.48% for Cd2+) and in industrial wastewater (recovery = 14.16% for Cd2+) were also investigated. Conditional stability constants (log K) of PA-Cu and PA-Cd complexes were determined as 6.98 and 5.61, respectively, indicating strong interaction between PA and the metals.  相似文献   

12.
The utilization of Amberlite (IRP-69 ion-exchange resin, 100–500 wet mesh) as the binding phase in the diffusive gradients in thin films (DGT) technique has shown potential to improve the assessment of plant-available K in soils. The binding phase has recently been optimized by using a mixed Amberlite and ferrihydrite (MAF) gel which results in linear K uptake over extended deployment periods and in solutions with higher K concentrations. As restriction of K uptake by Ca on the Amberlite based resin gel has been previously proposed, potential competing effects of Ca2+, Mg2+ and NH4+ on K uptake by the MAF gel were investigated. These cations had no effect on K elution efficiency which was 85%. However, K uptake by the MAF gel was restricted in the presence of competing cations in solution. Consequently, the diffusion coefficient of K decreased in the presence of cations compared to previous studies but was stable at 1.12 × 10−5 cm2 s−1 at 25 °C regardless of cation concentrations. Uptake of K by the DGT device was affected by the presence of excessive Ca in more than 30% of twenty typical Australian agricultural soils. However, this problem could be circumvented by using a shorter deployment time than the normal 24 h. Moderate correlation of concentrations of K extracted by DGT with Colwell K (extracted by NaHCO3, R2 = 0.69) and NH4OAc K (R2 = 0.61) indicates that DGT measures a different pool of K in soils than that measured by the standard extractants used. In addition, the MAF gel has the ability to measure Ca and Mg simultaneously.  相似文献   

13.
2-Thiophenecarboxaldhyde is chemically bonded to silica gel surface immobilized monoamine, ethylenediamine and diethylenetriamine by a simple Schiff’s base reaction to produce three new SP-extractors, phases (I-III). The selectivity properties of these phases toward Hg(II) uptake as well as eight other metal ions: Ca(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) were extensively studied and evaluated as a function of pH of metal ion solution and equilibrium shaking time by the batch equilibrium technique. The data obtained clearly indicate that the new SP-extractors have the highest affinity for retention of Hg(II) ion. Their Hg(II) uptake in mmol g−1 and distribution coefficient as log Kd values are always higher than the uptake of any other metal ion along the range of pH used (pH 1.0-10.0). The uptake of Hg(II) using phase I was 2.0 mmol g−1 (log Kd 6.6) at pH 1.0 and 2.0. 1.8 mmol g−1 (log Kd 4.25), 1.6 mmol g−1 (log Kd 3.90) and 1.08 mmol g−1 (log Kd 3.37) at pH 3.0, 5.0 and 8.0, respectively. Selective separation of Hg(II) from the other eight coexisting metal ions under investigation was achieved successfully using phase I at pH 2.0 either under static or dynamic conditions. Hg(II) was completely retained while Ca(II), Co(II) and Cd(II) ions were not retained. Ni(II), Cu(II), Zn(II), Pb(II) and Fe(III) showed very low percentage retention values to be 0.74, 0.97, 3.5 and 6.3%, respectively. Moreover, the high recovery values (95.5 ± 0.5, 95.8 ± 0.5 and 99.0% ± 1.0) of percolating two liters of doubly distilled water, drinking tap water and Nile river water spiked with 5 ng/l of Hg(II) over 100 mg of phase I packed in a minicolumn and used as a thin layer enrichment bed demonstrate the accuracy and validity of the new SP-extractors for preconcentration of the ultratrace amount of spiked Hg(II) prior to the determination by borohydride generation atomic absorption spectrometry (AAS) with no matrix interference. The detection limit (3σ) for Hg(II) based on enrichment factor 1000 was 4.75 pg/ml. The precision (R.S.D.) obtained for different amounts of mercury was in the range 0.52-1.01% (N = 3) at the 25-100 ng/l level.  相似文献   

14.
Reaction of AlEt3 with 2-methyl-8-quinolinol gave ethylbis(2-methyl-8-quinolinolato)aluminum complex [Al(Et)(q′)2] 1. The complex 1 provided photoluminescent Al complexes by reactions with phenols, carboxylic acid, and H2O. The α-CH2 hydrogens in the Et group of 1 was diastereotropic as revealed by 1H NMR spectroscopy because of the presence of a chiral center at Al. The chirality at Al was dynamically lost at elevated temperature in CDCl2CDCl2 and DMSO-d6, as indicated by temperature dependent 1H NMR spectroscopy. This dynamic or fluxional behavior of 1 is explained by rotation of the 2-methyl-8-quinolinolato ligand. The kinetic parameters of the dynamic process were estimated at ΔH = 135 kJ mol−1 and ΔS = 159 J K−1 mol−1 in CDCl2CDCl2 and at ΔH = 124 kJ mol−1 and ΔS = 151 J K−1 mol−1 in DMSO-d6, respectively, at 350 K. Structures of some of the obtained Al complexes were confirmed by single-crystal X-ray crystallography. These Al complexes showed photoluminescence peaks at 492-507 nm in CHCl3 with quantum yields of 7-23%.  相似文献   

15.
The performance characteristics of an alternative binding agent, suspended particulate reagent-iminodiacetate (SPR-IDA), for use with DGT methodology were investigated. The parameters investigated during this study included gel hydration, blank levels, elution factor (fe), capacity, the effects of pH on the binding of trace metals by DGT. The novel application of this resin for use as a quantitative standard for laser ablation ICP-MS was also evaluated. To further constrain the results for the SPR-IDA binding agent, parallel experiments were performed using resin gel containing Chelex 100, which has been widely reported in the literature. Hydration results showed that the SPR-IDA resin gel reached a stable dimension and weight within ∼30 min and was dimensionally stable for ≤6 months. The measured DGT blanks for the SPR-IDA resin were 0.0023, 0.15, 0.21, 0.0033 and 0.011 ng disc−1 for Co, Ni, Cu, Cd and Pb, respectively. The elution factor differed for the two resin types with the Chelex 100 recoveries slightly lower than previous reports and the SPR-IDA resin showing on average ∼5-9% better recoveries than DGT containing Chelex 100. The measured capacity of DGT discs containing the SPR-IDA binding agent was 0.26 mg Cd, similar to the calculated value of 0.29 mg Cd, indicating the entire resin layer was available for metal uptake.Both resin types performed equally well when deployed in 1 mM NaNO3 solutions with DGT measurements of ∼100% of direct solution measurements for Co, Ni and Cd. However, DGT measurements of Cu and Pb systematically decreased with increasing solution pH down to ∼50% of solution values at pH 8.0, due to artifacts resulting from colloid formation during the addition of the metals. This was remedied by adding the metals as dilute salt standards and addition of Mg(NO3)2 to eliminate adsorption to the container walls. In the latter experiments, DGT measured concentrations of Co, Ni, Cu, Cd and Pb were in agreement with solution concentrations. Deployment of DGT in solutions with increasing concentrations of trace metals yielded linear results, suggesting that quantitative analysis using simplified laser ablation techniques should be possible using this newly characterized SPR-IDA resin gel.  相似文献   

16.
Hydroboration reactions of 1-octene and 1-hexyne with H2BBr·SMe2 in CH2Cl2 were studied as a function of concentration and temperature, using 11B NMR spectroscopy. The reactions exhibited saturation kinetics. The rate of dissociation of dimethyl sulfide from boron at 25 °C was found to be (7.36 ± 0.59 and 7.32 ± 0.90) × 10−3 s−1 for 1-octene and 1-hexyne, respectively. The second order rate constants, k2, for hydroboration worked out to be 7.00 ± 0.81 M s−1 and 7.03 ± 0.70 M s−1, while the overall composite second order rate constants, k K, were (3.30 ± 0.43 and 3.10 ± 0.37) × 10−2 M s−1, respectively at 25 °C. The entropy and enthalpy values were found to be large and positive for k1, whilst for k2 these were large and negative, with small values for enthalpies. This is indicative of a limiting dissociative (D) for the dissociation of Me2S and associative mechanism (A) for the hydroboration process. The overall activation parameters, ΔH and ΔS, were found to be 98 ± 2 kJ mol−1 and +56 ± 7 J K−1 mol−1 for 1-octene whilst, in the case of 1-hexyne these were found out to be 117 ± 7 kJ mol−1 and +119 ± 24 J K−1 mol−1, respectively. When comparing the kinetic data between H2BBr·SMe2 and HBBr2·SMe2, the results showed that the rate of dissociation of Me2S from H2BBr·SMe2 is on average 34 times faster than it is in the case of HBBr2·SMe2. Similarly, the rate of hydroboration with H2BBr·SMe2 was found to be on average 11 times faster than it is with HBBr2·SMe2. It is also clear that by replacing a hydrogen substituent with a bromine atom in the case of H2BBr·SMe2 the mechanism for the overall process changes from limiting dissociative (D) to interchange associative (Ia).  相似文献   

17.
Commercially available Diphonix® resin (TrisKem International) was evaluated as a receiving phase for use with the diffusive gradients in thin-films (DGT) passive sampler for measuring uranium. This resin has a high partition coefficient for actinides and is used in the nuclear industry. Other resins used as receiving phases with DGT for measuring uranium have been prone to saturation and significant chemical interferences. The performance of the device was evaluated in the laboratory and in field trials. In laboratory experiments uptake of uranium (all 100% efficiency) by the resin was unaffected by varying pH (4–9), ionic strength (0.01–1.00 M, as NaNO3) and varying aqueous concentrations of Ca2+ (100–500 mg L−1) and HCO3 (100–500 mg L−1). Due to the high partition coefficient of Diphonex®, several elution techniques for uranium were evaluated. The optimal eluent mixture was 1 M NaOH/1 M H2O2, eluting 90% of the uranium from the resin. Uptake of uranium was linear (R2 = 0.99) over time (5 days) in laboratory experiments using artificial freshwater showing no saturation effects of the resin. In field deployments (River Lambourn, UK) the devices quantitatively accumulated uranium for up to 7 days. In both studies uptake of uranium matched that theoretically predicted for the DGT. Similar experiments in seawater did not follow the DGT theoretical uptake and the Diphonix® appeared to be capacity limited and also affected by matrix interferences. Isotopes of uranium (U235/U238) were measured in both environments with a precision and accuracy of 1.6–2.2% and 1.2–1.4%, respectively. This initial study shows the potential of using Diphonix®-DGT for monitoring of uranium in the aquatic environment.  相似文献   

18.
The properties of the iron(III) complexes of the ditopic macrocyclic ligand with three aminopropyl pendant arms, L1 = 3,7,11-tris-(3-aminopropyl)-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene were investigated in aqueous solution. Potentiometric studies indicated the presence of mononuclear [FeHhL1]h+3 (h = 0–3), and dinuclear [Fe2L1]6+, [Fe2L1(OH)]5+ and [Fe2L1(OH)2]4+ complexes, and their stability constants were determined at 298.2 K and ionic strength 0.10 mol dm−3 in KNO3. The log K values of mononuclear protonated species indicated the consecutive deprotonation of the aminopropyl arms, suggesting the nitrogen donor atoms from the macrocycle as the preferred coordination environment for the first metal centre, and the amines from the pendant arms for the second one. The dinuclear complex is formed at about 85% of the total amount of the metal ion for 2:1 Fe:L1 ratio solutions at pH 4.0–4.5. The log K values of the deprotonation of dinuclear hydrolysed species are consistent with the presence of two water molecules directly bound to the metal centres. Spectroscopic UV–Vis and IR data for 2:1 Fe3+:L1 ratio samples confirmed the existence of dinuclear and hydroxo dinuclear species. EPR spectra of these solutions were interpreted by an equilibrium of two high-spin d5 state of iron(III) species with different rhombic E/D distortions. Electrochemical studies also established the formation of mono- and dinuclear complexes, showing irreversible redox behaviour. The two metal centres on the dinuclear complexes have only weak interactions.  相似文献   

19.
The behaviour of solutions of the sodium salt of 4-(2,4-dinitrophenyl)pentanoic acid in D2O is readily monitored by 1H NMR spectroscopy. In the presence of excess NaOD, these show exchange of hydrogen at the 3-position of the benzene ring with kOD = 1.23(0.03) × 10−4 M−1 s−1 at 25 °C. Rates of exchange using solutions with triethylamine buffers show no dependence on buffer concentration and an estimate of the acid dissociation constant, pK≈ 29.3, of the dinitrobenzene is made. Under the conditions, there is no detectable exchange at the benzylic position.  相似文献   

20.
The hydrogen peroxide-oxidation of o-phenylenediamine (OPD) catalyzed by horseradish peroxidase (HRP) at 37 °C in 50 mM phosphate buffer (pH 7.0) was studied by calorimetry. The apparent molar reaction enthalpy with respect to OPD and hydrogen peroxide were −447 ± 8 kJ mol−1 and −298 ± 9 kJ mol−1, respectively. Oxidation of OPD by H2O2 catalyzed by HRP (1.25 nM) at pH 7.0 and 37 °C follows a ping-pong mechanism. The maximum rate Vmax (0.91 ± 0.05 μM s−1), Michaelis constant for OPD Km,S (51 ± 3 μM), Michaelis constant for hydrogen peroxide Km,H2O2 (136 ± 8 μM), the catalytic constant kcat (364 ± 18 s−1) and the second-order rate constants k+1 = (2.7 ± 0.3) × 106 M−1 s−1 and k+5 = (7.1 ± 0.8) × 106 M−1 s−1 were obtained by the initial rate method.  相似文献   

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