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以布洛芬乙酯为反应底物,探索了酶促水解法拆分布洛芬的工艺.以曲拉通X-100为表面活性剂,利用南极假丝酵母脂肪酶B(CAL-B)催化拆分外消旋布洛芬乙酯,并对表面活性剂含量、有机溶剂种类和添加量、酶量、缓冲溶液pH、温度及时间等反应条件进行了优化,得到的最佳反应条件为:在pH为9.0的缓冲溶液中,添加80 mg曲拉通X-100、 50μL二氯甲烷和15 mg CAL-B,于30℃下反应48 h,在该条件下,S-布洛芬乙酯的剩余率(C)为65%,布洛芬乙酯的对映体过量值(ee_s)为94%. 相似文献
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基于非离子表面活性剂Triton X-100,以浊点萃取结合荧光光度法测定水中的苯酚,考察影响浊点萃取的各种因素。在pH=3.0的磷酸氢二钠-磷酸二氢钾缓冲溶液中,采用2.0mL Triton X-100(5%)、82℃平衡温度、8min平衡时间的条件下,苯酚被萃取到Triton X-100表面活性剂相与水相分开,用于环境水样中苯酚的测定,结果令人满意。 相似文献
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表面活性剂对脂肪酶活性和选择性的影响 总被引:6,自引:0,他引:6
考察了几种表面活性剂对lipaseOF粗酶和纯化酶催化拆分酮基布洛芬的影响。除吐温-80,吐温-60和壬基酚聚氧乙烯醚外,大部分表面活性剂对酶活性有抑制作用,其中只有吐温-80能显著提高酶的立体选择性。酶的活性和选择性与表面活性剂浓度有关。在表面活性剂浓度为最佳(20mg/mL吐温-80或30mg/mL壬基酚聚氧乙烯醚)时lipaseOF粗酶的活性可分别提高13和15倍。加入80mg/mL吐温-80,粗酶和纯化酶的对映体选择率(E值)分别由1.1和8.0增至6.7和>100。 相似文献
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基于非离子表面活性剂TritonX-100,以浊点萃取结合荧光光度法测定水中的苯酚,考察影响浊点萃取的各种因素。最佳实验条件为:pH=3.0的磷酸氢二钠-磷酸二氢钾缓冲溶液中,5%的TritonX-100用量2.0mL、平衡温度82℃、平衡时间8min。在此条件下,苯酚被萃取到TritonX-100表面活性剂相与水相分开。 相似文献
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吐温-80对固定化脂肪酶催化酮基布洛芬氯乙酯对映体选择性水解反应的影响 总被引:2,自引:0,他引:2
酮基布洛芬为2-芳基丙酸类非甾体抗炎药的一种,其药效与立体构型有很大关系[1].生物法催化的动力学拆分是获得单一对映体酮基布洛芬的有效方法之一[2,3].最近,我们发现在利用皱褶假丝酵母(Candida rugosa)脂肪酶Lipase OF催化拆分酮基布洛芬氯乙酯时,向反应体系中加入非离子表面活性剂吐温-80,不仅可大幅度提高反应速度,而且更重要的是解决了原来Lipase OF选择性较差的问题,从而为酮基布洛芬的对映体拆分提供了一种新方法. 相似文献
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在pH 3.6乙酸-乙酸钠缓冲溶液中,在曲拉通X-100存在下,锌(Ⅱ)与硫氰酸钾和藏红T(ST)反应生成稳定的离子缔合物[ST]4[Zn(SCN)6]。离子缔合物的最大吸收波长为482nm,锌(Ⅱ)的质量浓度在0.006~0.70mg.L-1范围内符合比耳定律,表观摩尔吸光率为5.41×104L.mol-1.cm-1... 相似文献
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非离子表面活性剂水溶液中木素过氧化物酶催化氧化藜芦醇反应稳态动力学研究 总被引:2,自引:0,他引:2
研究表面活性剂缔合体系中木素模型化合物的生物降解机制具有重要意义。本文以黄孢原毛平革菌在一定条件下分泌出的木素过氧化物酶(LiP)为生物催化剂,用分光光度技术研究了非离子表面活性剂TritonX-100存在下水溶液中LiP催化氧化藜芦醇(VA)反应的动力学。结果表明,在TritonX-100水溶液中,LiP催化氧化VA反应遵循乒乓机。稳态动力学参数测定表明,TritonX-100对上述酶促反应的最大反应初速率及VA的米氏常数影响不大,但使过氧化氢的米氏常数下降近50%。依据不同Triton-100浓度下(远低于、接近于和远大于其临界胶束浓度)酶促反应的动力学参数和VA的疏水性指数,我们认为该结果是表面活性剂单体对酶蛋白分子的修饰所致。 相似文献
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The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted
indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator
model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was
established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing
analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997. 相似文献
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Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position. 相似文献
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The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations
were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples
were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of
hematite Fe2O3. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the
best fitting experimental data.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Cyclopropyl derivative of 2,6-di-tert-butylphenol is synthesized as a probe to investigate the mechanism of base-catalyzed autooxidation of phenol derivatives. Our study indicates that one electron reduction of molecular oxygen from phenolate gives phenoxyl radical 3, a key intermediate of autooxidation. The coupling of phenoxyl radical and superoxide radical gives peroxylate anion 4 and produces the final epoxy alcohol adduct 6. 相似文献
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微量钙的测定方法研究进展 总被引:5,自引:0,他引:5
介绍了1995-2006年期间测定微量和痕量钙的方法,如电感耦合等离子体-原子发射光谱法、原子吸收光谱法以及离子色谱法等的工作原理和特点,并说明了其测定微量钙的应用领域。并对微量钙的测定技术进行了展望(引用文献55篇)。 相似文献
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Thermal behaviour of sodium oxo-salts of sulphur: Na2SO4, Na2S2O7, Na2S2O6, Na2SO3, Na2S2O5, Na2S2O4, Na2S2O3, Na2S3O6 and of sulphides Na2S and Na2S2 was studied on heating up to 1000°C. The experiments were performed with anhydrous compounds obtained from commercial products
by recrystallisation and dehydration. The stage mechanisms of decomposition of anionic sub-lattices of the salts have been
proposed basing on the Górski’s morphological classification of simple species. The thermal stability and the stage decomposition
mechanisms were correlated with the structure and the potential chemical properties of the salt anions. The thermal decomposition
processes were studied by means of thermal analysis, and the decomposition products were identified by means of X-ray phase
analysis. 相似文献