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21.
Francesco Trotta Giancarlo Cravotto Stefano Rossignoli 《Journal of inclusion phenomena and macrocyclic chemistry》2002,44(1-4):293-296
Oxidative couplings of 2-naphthol, 6-bromo-2-naphthol and2-naphthylamine were achieved at room temperature in the presence of H2O2, horseradish peroxidase and a suitable cyclodextrin.2-Thionaphthol behaved differently, yielding the corresponding disulfide. Yields of binaphthyl derivatives were generally excellent, and a fairly good enantiomeric excess was observed. Under similar reaction conditions methyl 2-(6-methoxy-2-naphthyl) propanoate, when treated with esterase in the presence of cyclodextrin, yielded naproxen (a well-known anti-inflammatory drug) with a good enantiomeric excess. No reaction product was detected in the absence of cyclodextrin. Cyclodextrins do not act as simple transfer agents. 相似文献
22.
V. Vojinovi? 《Analytica chimica acta》2006,565(2):240-249
A new alternative method for bioprocess monitoring based on bienzymatic analytical microreactors integrated in a flow injection analysis (FIA) system is described. Glucose-, alcohol-, lactate-, galactose- and l-amino acid oxidases (GO, AO, LacO, GalO and LAAO) and horseradish peroxidase (HRP) are immobilized on controlled pore glass (CPG) and used for the development of glucose, ethanol, lactate, galactose and amino acid sensors. The analytical methodology is based on HRP catalysed reaction of hydrogen peroxide produced by oxidases with phenol-4-sulfonic acid and 4-aminoantipyrine. The immobilized enzymes are characterized and used for preparation of the packed bed analytical microreactors. Shelf life and operational stability of the microeactors are determined. GO/HRP, AO/HRP and LAAO/HRP microreactors showed excellent shelf life, they could be stored and reused for more than 6 months with no or very little activity loss, while GalO/HRP and LacO/HRP could be stored for shorter periods of time (10-20 days). Operational stability of GO and LacO microreactors was very good: an equivalent to 16,900 FIA injections of 25 μl to a LacO microreactor resulted in loss of half of its activity, immobilized GO was so stable that it was impossible to evaluate enzyme halflife. Immobilized GalO and LAAO lose their operational activity much faster: approximately 1400 and 8000 FIA injections of the respective substrate solution in a FIA set-up resulted in 50% activity loss. The methods with all the described microreactors were successfully validated using off-line samples from S. cerevisiae, E. coli and mesenchymal stem cell cultures with HPLC as the reference method. 相似文献
23.
24.
Yannis Dotsikas 《Analytica chimica acta》2004,509(1):103-109
This study describes the employment of a novel imidazole-substituted phenol [4-(1-imidazolyl)phenol] as a highly potent signal enhancer in a horseradish peroxidase (HRP)-luminol chemiluminescence (CL) immunoassay. This competitive-type immunoassay for the model antigen fentanyl is based on the use of fentanyl polyclonal antibody immobilized on white microtiter plates and a biotinylated bovine serum albumin (BSA)-fentanyl derivative as a tracer. The latter was detected by means of streptavidin labeled with HRP, resulting in the generation of a high-intensity and relatively stable chemiluminescent signal, immediately after the addition of the substrate solution (NOAS). The developed method fulfilled the requirements of accuracy (percentage recovery ranged from 93.8 to 107%) and precision (intra- and inter-assay CVs were 2.5-5.2 and 4.5-11.9%, respectively). Its plasma detection limit (1.05 pg ml−1) was lower than those of previous immunoassays. The novel assay was compared in terms of sensitivity and concentration range with other common HRP substrate systems: luminol-p-iodophenol-H2O2 and TMB-H2O2. Finally, the described method was compared with an HRP-fentanyl conjugate-based assay, similar to commercially available kits (SKIT), employing the novel substrate solution for both assays and the differences observed were explained by applying previously described models. The detection limit was 4.82 pg ml−1 for SKIT, recovery values were 94.2-105% and intra- and inter-assay CVs were 2.5-5.2 and 4.5-11.9%, respectively. In conclusion, the proposed assay could be utilized for a wide range of molecules and replace the existing enzyme-labeled antigen-based kits. 相似文献
25.
Transition state analogues (TSAs) have long been regarded as ideal templates for the preparation of catalytically active synthetic imprinted polymers. In the current work, however, a new type of molecularly imprinted polymer (MIP) was synthesized with the substrate (homovanillic acid, HVA) as the template and hemin introduced as the catalytic center, with the use of plural functional monomers to prepare the active sites. The MIP successfully mimicked natural peroxidase, suggesting that it may not be imperative to employ a TSA as the template when preparing enzyme-like imprinted polymers and that the imprinted polymer matrix provided an advantageous microenvironment around the catalytic center (hemin), essentially similar to that supplied by apo-proteins in natural enzymes. Significantly, by taking advantage of the special structure of hemin and multiple-site interactions provided by several functional monomers, the intrinsic difficulties for MIPs in recognizing template molecules in polar solutions were overcome. The newly developed polymer showed considerable recognizing ability toward HVA, catalytic activity, substrate specificity and also stability, which are the merits lacked by the natural peroxidase. Meanwhile, the ease of recovery and reuse the MIP implies the potential for industrial application. 相似文献
26.
化学发光单孵多层免疫技术检测粪样中轮状病毒 总被引:3,自引:0,他引:3
以酶联免疫吸附分析(ELISA)夹心测定粪样中轮状病毒(RV)实验为模型,将传统又孵式免疫操作变成单孵式,即在包被RV抗体Ab的微孔中同时加入含RV的粪样上清液和根过氧化物酶(HRP)标记抗RV抗原共同孵育,其结果在载体表面形成多层酶免疫复合物,以HRP催化鲁米诺-对碘苯酚-过氧化氢化学体系作为最终信号检测系统,从而建立起化学发光单孵多层免疫技术(CL-SIMIT)。其灵敏度是ELISA的16倍, 相似文献
27.
Laura S. Zamorano Francisco Gavilanes Ivan Yu. Sakharov Robert B. van Huystee Valery L. Shnyrov 《Thermochimica Acta》2004,417(1):67-73
Detailed differential scanning calorimetry (DSC), steady-state tryptophan fluorescence and far-UV circular dichroism (CD) studies, together with enzymatic assays, were carried out to monitor the thermal stability of anionic peanut peroxidase (aPrx) at pH 3.0. The spectral parameters were seen to be good complements to the highly sensitive but integral method of DSC. Thus, changes in far-UV CD corresponded to changes in the overall secondary structure of the enzyme, while changes in intrinsic tryptophan fluorescence emission corresponded to changes in the tertiary structure of the enzyme. The results, supported with data concerning changes in enzymatic activity with temperature, show that thermally induced transitions for aPrx are irreversible and strongly dependent upon the scan rate, suggesting that denaturation is under kinetic control. It is shown that the process of aPrx denaturation can be interpreted with sufficient accuracy in terms of the simple kinetic scheme, , where k is a first-order kinetic constant that changes with temperature, as given by the Arrhenius equation; N is the native state, and D is the denatured state. On the basis of this model, the parameters of the Arrhenius equation were calculated. 相似文献
28.
The enzymatic nitration of phenol and m-cresol catalyzed by horseradish peroxidase was studied in the presence of H2O2 and NaNO2. The results showed that the nitration products of phenol were 2-nitro and 4-nitrophenols. There was also a small amount of by-products of hydroquinone and catechol. The influences of various reaction parameters, including pH, organic solvent type, and concentrations of NaNO2 and H2O2, on the nitration products were investigated. The yields of 4-nitrophenol and 2-nitrophenol were 14% and 12%, respectively. The nitration products of m-cresol were 4-nitro-m-cresol and 6-nitro-m-cresol, and the yields of 4-nitro-m-cresol and 6-nitro-m-cresol were 19% and 30%, respectively. 相似文献
29.
J. Díaz-Ferrero M.C. Rodríguez-Larena L. Comellas B. Jiménez 《Trends in analytical chemistry : TRAC》1997,16(10):1865-573
The usual methods for determining polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF) and polychlorinated biphenyls (PCB) are generally expensive and time consuming. This fact has favored the development of faster and cheaper techniques, based on immunoassays and bioassays. This paper reviews these bioanalytical methods and their analytical importance at the present moment. 相似文献
30.
LIN Feng LI Ying YANG Wen-kui LIANG Bing MU Ying SUN Ye LI Wei LUO Gui-min 《高等学校化学研究》2007,23(1):58-63
IntroductionReactive oxygen species(ROS) are known to de-stroy biomacromolecules and cause cell injury[1]. Un-der normal circumstances, there is a balance betweenthe production of ROS and their destruction. Many dis-eases, such as brain ischemia, tumor, v… 相似文献