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非水介质中的酶催化反应 总被引:6,自引:0,他引:6
介绍了非水溶剂体系中的酶催化反应,主要是反胶束体系中酶催化反应和脂肪酶催化反应的新研究成果,评述了各溶剂体系中酶的结构,动力学特征,稳定性及活性。 相似文献
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综述了铟、锌、锡等金属(试剂)诱导的,在水介质中进行的Barbier-Grignard反应,并讨论了该反应的化学选择性、区域选择性和立体选择性。 相似文献
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非水溶剂中酶反应研究进展 总被引:7,自引:0,他引:7
本文报道了在非水溶剂系统中进行酶促反应的最新进展。对于酶反应的低水体系与必需水,酶活性与非水介质性质之间的关系,疏水参数logP,介质工程与酶经酶经配体印迹后,其活性比未经印迹的酶活性明显提高等进行了介绍,并举例说明了在非水溶剂中进行酶促反应的应用前景。 相似文献
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生物活性肽 ,特别是寡肽 ,在免疫调节、激素调节、酶抑制、抗菌、抗病毒等方面有很大的应用潜力[1] .另外 ,调味肽也越来越显示出其在应用上的重要性 .肽作为一种终产品或者前体物质 ,在食品和药物生产上的商业潜力非常巨大 ,从而促进了肽合成的研究和发展 .目前肽合成主要有 3种方法 :化学法、重组DNA技术、酶法 .每种方法都有其优点和缺点 .总体上来说 ,在工业上化学法仍然使用得最多 ,其热力学动力学模型已经很好地建立起来 ;重组 DNA技术 ,由于需要一个长期、昂贵的研究和发展阶段 ,而且在发酵阶段存在表达效率低和产品提取回收困难… 相似文献
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酶在有机溶剂中催化作用的研究日益受到重视,其应用范围也越来越广.本文就有机介质中酶催化的基本原理进行了讨论,包括酶的结构和催化机理,以及溶剂和水对酶的结构和催化功能的影响.同时,本文归纳出提高酶活性的一系列方法,其中不少方法简便易行,能使酶活性提高102-105倍. 相似文献
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Huan Dong Shu‐Gui Cao Zheng‐Qiang Li Si‐Ping Han De‐Lin You Jia‐Cong Shen 《Journal of polymer science. Part A, Polymer chemistry》1999,37(9):1265-1275
Polymerization of several lactones were carried out by employing Pseudomonas sp. lipase as the catalyst. The data indicate that water is consumed at the onset of polymerization and released in part during subsequent stages, leading us to propose a complex mechanism for the enzymatic polymerization of lactone. This mechanism involves both ring‐opening and linear condensation polymerization. The former was dominant at the early stage while the latter was dominant in the later stage. In addition, the reaction media showed complex influences on enzymatic polymerization. Some organic solvents increased the degree of polymerization (DP) and decreased the molecular weight distribution. A strategy to increase the molecular weight of the polymer is introduced, which led to the synthesis of a polymer with a number‐average molecular weight (Mn) of 14,500—the highest Mn of poly(ε‐caprolactone) prepared by enzyme‐catalyzed polymerization thus far—and molecular weight distribution of 1.23. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1265–1275, 1999 相似文献
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A simple potentiometric method for the determination of organoisothiocyanates is described. The isothiocyanate is treated in acetonitrile medium with an excess of primary amine to convert it into a substituted thiourea and the surplus amine is converted into a dithiocarbamate by addition of carbon disulphide. The solution is then titrated with a copper(II) solution in acetonitrile. The three-step titration curve enables the results to be calculated on the bash of the dithiocarbamate and/or thiourea formed. The method has been successfully applied to the analysis of a commercial insecticide formulation based on isothiocyanate and important mixtures containing isothiocyanates. 相似文献
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S. S. E. H. Elnashaie G. Ibrahim S. S. Elshishini 《Applied biochemistry and biotechnology》1984,9(5-6):455-474
The present investigation concentrates on the study of the complex phenomenon of multiplicity in membranes carrying substrate-inhibited,
hydrogen ion-sensitive enzyme. The investigation takes into consideration both symmetrical and asymmetrical steady states.
The number of steady states (symmetrical and asymmetrical) found in this case is quite large, giving rise to multiple hysteresis
loops and multiple “isolas.” 相似文献
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S. G. Christov 《International journal of quantum chemistry》2001,81(1):1-3
A reaction rate theory for dense‐phase reactions, based on the assumption of nonlinear coupling between reactant and medium, is proposed. The relations between the exact dynamic theory, the stochastic rate theory, and the transition state theory is discussed. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 81: 1–3, 2001 相似文献
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Cheves Walling 《Tetrahedron》1985,41(19):3887-3900
Properties of radical chain reactions are reviewed including propagating steps, lifetimes of chains, and choices of initiators. Structure and reactivity relations in chain-propagation steps and their effects on regio- and stereochemistry are discussed. The utility of redox chains involving transition metal ions is considered along with the importance of radical ions as reaction intermediates. 相似文献
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Bartosz Nowosielski Marzena Jamrgiewicz Justyna uczak Dorota Warmiska 《Molecules (Basel, Switzerland)》2022,27(3)
This paper demonstrates the assessment of physicochemical and thermodynamic properties of aqueous solutions of novel deep eutectic solvent (DES) built of tetrabutylammonium chloride and 3-amino-1-propanol or tetrabutylammonium bromide and 3-amino-1-propanol or 2-(methylamino)ethanol or 2-(butylamino)ethanol. Densities, speeds of sound, refractive indices, and viscosities for both pure and aqueous mixtures of DES were investigated over the entire range of compositions at atmospheric pressure and T = (293.15 ‒ 313.15) K. It was concluded that the experimental data were successfully fitted using the Jouyban–Acree model with respect to the concentration. Obtained results showed that this mathematical equation is an accurate correlation for the prediction of aqueous DES properties. Key physicochemical properties of the mixtures—such as excess molar volumes, excess isentropic compressibilities, deviations in viscosity, and deviations in refractive indices—were calculated and correlated by the Redlich–Kister equation with temperature-dependent parameters. The non-ideal behavior of the studied systems were also evaluated by using the Prigogine−Flory−Patterson theory and the results were interpreted in terms of interactions between the mixture components. 相似文献
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随着人们生活水平的提高和健康意识的增强,食品安全越来越受到关注.非酶催化分析法具有灵敏度高,且操作简单,检测快速的特点,本文综述了近年来非酶催化法在食品铜含量测定中的应用情况,分析了其局限性,并对其应用前景进行了展望. 相似文献
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J. G. March J. K. Amartey W. Wolf 《Journal of Radioanalytical and Nuclear Chemistry》1989,132(2):293-303
Prior work had documented that99mTcCl
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2–
could undergo ready ligand exchange reaction under non-aqueous condition. We now wish to report the ligand exchange reaction of bromine in99mTcBr
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in non-aqueous solvents using 8-hydroxyquinoline (oxine) as the displacing ligand. Analysis of the products obtained by paper chromatography, HPLC and electrophoresis suggest that a 12 Tcoxine complex appears to be the most stable of the complexes formed, probably99mTc(oxine)2 Br2. However, displacement of bromine by polar solvents (both protic and aprotic) can also occur, both on99mTcBr
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2–
and in the above complex as a consequence of solvolytic reactions. Other Tc-oxine complexes can also be formed upon ligand exchange, but they appear to be stable only under aprotic, non solvolytic conditions. These studies again document that hexahalotechnetate complexes exhibit ligand exchange reactions under non-aqueous conditions, that they allow the ready synthesis of novel technetium complexes, but that because of their high reactivity the effect of competing reactions must be considered. 相似文献
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《Green Chemistry Letters and Reviews》2013,6(4):707-725
Abstract There is a growing interest in applying green chemistry for nanocatalysis applications. On the basis of a Scifinder Scholar search, the field of applying green chemistry to catalysis with nanoparticles has undergone an explosive growth from year 2002 to present. It can be seen that green chemistry applied to nanocatalysis is a relatively hot area with much room for growth. I discuss several review articles written about the use of green nanocatalysts as well as green reactions. I discuss studies involving the synthesis of green nanocatalysts and application of metal nanocatalysts in green reactions. I have organized the discussion of green nanocatalysts by the type of nanoparticles that are synthesized and used as catalysts. I have organized discussions of green reactions by the type of green reaction that is being conducted. Overall, our review article discusses developments in new types of green nanocatalysts as well as developments in green catalytic reactions. 相似文献
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The generation of BiH3 in non-aqueous media in an MHS-10 Perkin-Elmer hydride generator is studied. Optimal conditions for generation of BiH3 inN,N-dimethylformamide, dimethylsulfoxide and formamide (concentration of NaBH4, acidic medium, optimum volume, characteristic concentration and detection limit) are studied. The results obtained are compared with those corresponding to hydride generation in aqueous medium. 相似文献