界面活化的溶胶凝胶包埋Candida rugosa脂肪酶催化合成维生素E琥珀酸酯

采用界面活化的溶胶凝胶包埋Candida rugosa脂肪酶(CRL)催化合成了维生素E琥珀酸酯.考察了影响溶胶凝胶包埋固定化CRL的因素,获得的最佳固定化条件为:丙基三甲氧基硅烷/正硅酸四乙酯摩尔比为1/1,水与硅烷前体摩尔比为15,酶的添加量为0.5mg/ml,PEG400的添加量为12μl/ml溶胶. 溶胶凝胶包埋的CRL在50℃,18h后其活性仍然保持了70.58%,是游离酶的2.6倍,且稳定性得到了明显的改善.基于CRL的界面特性,采用五种表面活性剂对其进行界面活化.结果表明,采用橄榄油活化的溶胶凝胶包埋的CRL合成维生素E琥珀酸酯的酯化活力最高,相比原酶和未界面活化的溶胶凝胶包埋酶分别提高了6.7和1.43倍.     

Candida rugosa Lipase－catalyzed Kinetic Resolution of Hydroxyalkanephosphonates

An efficient lipase-catalyzedenantioselective hydrolysis of butyryloxyalkanephosphonates in water-equillbrated diisopropyl ether was developed. The relationship between the substrates‘ structure and the reactivity, as well as the enantioselectivlty of this enzymatic transformation was studied. The catalytic preference of crude Candida rugosa lipase toward such molecules was assigned according to modified Mosher‘s method and Xray crystallographic analysis. Optically pure 2-hydroxy-2-arylethanephosphonates, 3-hydroxy-3-phenylpropanephosphonate, and 3, 3, 3-trifluoro-2-hydroxypropanephosphonates were conveniently prepared in this manner.     

离子液体中聚乙二醇维生素E琥珀酸酯的合成

以离子液体为催化剂,由维生素E经两步酯化反应合成了聚乙二醇1000(PEG1000)维生素E琥珀酸酯。以离子液体1-(N',N'-二甲胺乙基)-3-甲基咪唑四氟硼酸盐为催化剂、1,2-二氯乙烷为助溶剂、维生素E与琥珀酸酐摩尔比为1:1.2,在80 ℃条件下反应4 h,维生素E琥珀酸酯(TAS)的产率为90%。以1-丙磺酸基-3-甲基咪唑硫酸氢盐/甲苯为反应体系,TAS与PEG1000摩尔比为1:2,在100 ℃下反应5 h,PEG1000维生素E琥珀酸酯(TPGS)收率为91%。     

柱状假丝酵母脂肪酶同工酶的一种高效液相色谱分离新方法

建立一种“疏水界面亲和色谱”分离柱状假丝酵母脂肪酶同工酶的高效液相色谱新方法。将商品化的CRL经离子交换色谱分离为两个同工酶组分 (CRLA和CRLB) ,在极低离子强度下 ,根据同工酶活性中心周围处于“开放”构象的疏水腔具亲疏水界面的特性 ,用疏水界面亲和色谱在NucleosilC4 (10 μ ,3 0 0 ,2 5 0× 4.60mm)柱上将CRLA和CRLB都分离为 4种同工酶组分。疏水界面亲和色谱非常适用于分离这种结构差异轻微的同工酶组分     

维生素E的不对称合成

系统地综述了维生素E的合成方法, 旨在为进行维生素E及其相关萜类化合物合成的研究人员提供参考.     

SBA-15固定化脂肪酶催化拆分萘普生甲酯水解反应

利用吸附法将柱状假丝酵母菌脂肪酶(Candida rugosa lipase,CRL)固定于SBA-15介孔分子筛上,在搅拌槽反应体系中催化拆分外消旋萘普生甲酯的水解反应,获得了光学纯对映体(S)-萘普生,考察了SBA-15性能和酶固定量对初始反应速率、产量、转化率、对映体过剩(eep)和对映体选择性(E)的影响.结果...     

Covalent attachment of Candida rugosa lipase on chemically modified hybrid matrix of polysiloxane-polyvinyl alcohol with different activating compounds

Candida rugosa lipase was immobilized by covalent binding on hybrid matrix of polysiloxane–polyvinyl alcohol chemically modified with different activating agents as glutaraldehyde, sodium metaperiodate and carbonyldiimidazole. The experimental results suggested that functional activating agents render different interactions between enzyme and support, producing consequently alterations in the optimal reaction conditions. Properties of the immobilized systems were assessed and their performance on hydrolytic and synthetic reactions were evaluated and compared with the free enzyme. In hydrolytic reactions using p-nitrophenyl palmitate as substrate all immobilized systems showed higher thermal stability and optima pH and temperature values in relation to the free lipase. Among the activating compounds, carbonyldiimidazole resulted in a total recovery of activity on the support and the highest thermal stability. For the butyl butyrate synthesis, the best performance (molar conversion of 95% and volumetric productivity of 2.33 g L⁻¹ h⁻¹) was attained with the lipase immobilized on POS–PVA activated with sodium metaperiodate. The properties of the support and immobilized derivatives were also evaluated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopies and chemical composition (FTIR).     

维生素E母核合成研究进展

综述了2,3,5-三甲基氢醌的合成工艺进展,主要包括2,3,6-三甲基苯酚(TMP)氧化还原法、TMP羟基化法与异佛尔酮法,详细阐述了其中关键反应步骤的机理,并指出新型催化剂的开发与应用将是此领域的重点研究方向。     

Improvement of the Synthesis of Vitamin E Catalyzed by Montmorillonite

Abstract

Montmorillonite K 10 or montmorillonite K 10-supported metal salt as catalysts to synthesize VE (yield 21.0–64.4%) with 2,3,5-trimethylhydroquinone and isophytol. The catalysts can be reused.     

混合溶剂中酶促合成维生素A乳酸酯

研究了混合溶剂中脂肪酶催化合成维生素A乳酸酯.首先对催化合成维生素A乳酸酯反应的脂肪酶和反应介质进行了研究,其次对影响合成维生素A乳酸酯反应的因素(温度、底物摩尔比、反应时间和酶量等)进行了探讨,优化了反应条件:在5 mL混合溶剂(叔丁醇/正己烷(v/v)=3:2)中,0.167 g维生素A醋酸酯和0.150g乳酸在25 mg脂肪酶Novozym 435催化下,在35℃、150 r/m in下反应6 h,产率可以达到52.19%,固定化酶可连续使用5次以上,产率仍达45%以上.     

Immobilization of lipase from Candida rugosa on layered double hydroxides for esterification reaction

Synthesis of layered double hydroxides (LDHs) of Zn/Al-NO3- hydrotalcite (HIZAN) and Zn/Al-diocytyl sodium sulfosuccinate (DSS) nanocomposite (NAZAD) with a molar ratio of Zn/Al of 4:1 were carried out by coprecipitation through continuous agitation. Their structures were determined using X-ray diffractometer spectra, which showed that basal spacing for LDH synthesized by both methods was about 8.89 A. An expansion of layered structure of about 27.9 A was observed to accommodate the surfactant anion between the interlayer. This phenomenon showed that the intercalation process took place between the LDH interlayer. Lipase from Candida rugosa was immobilized onto these materials by physical adsorption method. It was found that the protein loading onto NAZAD is higher than HIZAN. The activity of immobilized lipase was investigated through esterification of oleic acid and 1-butanol in hexane. The effects of pore size, surface area, reaction temperature, thermostability of the immobilized lipases, storage stability in organic solvent, and leaching studies were investigated. Stability was found to be the highest in the nanocomposite NAZAD.     

Effect of fermentation conditions in the enzymatic activity and stereoselectivity of crude lipase from Candida rugosa

Different fed-batch cultures of Candida rugosa were carried out using oleic acid as the only carbon source. The crude lipases obtained under several operational conditions and downstream processes showed different catalytic activity and isoenzymes ratio. This fact implied that the performance of the lipase produced could be modulated by using different operational fermentation conditions. These powders were compared with commercial lipase from Sigma (St. Louis, MO) in hydrolysis and synthesis reactions. Especially interesting was the fact that the enantioselectivity of a crude lipase was higher than that observed with commercial lipase in the resolution of recemic Ketoprofen. In addition, response of both lipases in the presence of water was different.     

聚甲基丙烯酸羟乙酯载体固定化酵母脂肪酸在有机溶剂中催化酯合成反应的研究

用悬浮聚合法合成了一系列聚甲基丙烯酸羟乙酯载体，考察了它们固定化酵母脂肪酶活力与载体的交联度和致孔剂用量之间的关系。研究了这些固定化酵母脂肪酶在有机溶剂中催化酯合成反应的活性。脂肪酶的固定化使之活力表达更为充分，对亲水性较强的有机溶剂有更强的耐受性，并能为其在有机溶剂中催化酯合成反应提供必需水。考察了ｐＨ值，底物种类对固定化酵母脂肪酶催化酯合成反应的影响。     

有机相中脂肪酶催化合成乳酸乙酯

 考察了在双底物抑制下脂肪酶催化合成乳酸乙酯,最佳溶剂为叔丁醇,在所选的几种脂肪酶中,固定化于大孔丙烯酸树脂的南极假丝酵母脂肪酶B (Novozym 435)的催化活性最好. 对反应条件进行了优化,当酸醇摩尔比为1∶8, 反应温度60 ℃, 酸浓度0.3 mol/L, 酶浓度45 g/mol, 摇床转速200 r/min时产率达到77%, 脂肪酶Novozym 435重复使用6次后产率仍然可达到60%.     

气相色谱法测定化妆品中的 VE 含量

介绍了一种用气相色谱法准确快速测定品中ＶＥ２含量的新方法。该法以ＶＣ作保护剂,用环已烷提取样品,ＳＥＰ－ＰＡＫ ＡＬＵＭ－Ａ小柱净化。以氯氰菊酯内标物,在１？５％ＯＶ＝－１７色谱柱上进行分离,测定化妆口中ＶＥ含量。内标物与样品的分离度为１．５５。平均回收纺为９４．３％～９８．８％,相对标准偏差为１．７％～３．５％（ｎ＝５）。     

Polycondensation of Sebacic Acid with Primary and Secondary Hydroxyl Groups Containing Diols Catalyzed by Candida antarctica Lipase B

Abstract

The aliphatic polyesters are normally synthesized by ester interchange reactions or direct esterification of hydroxyacids or diacid/diol combinations. Biotransformation, utilizing the enzymes as catalysts, was accepted as an alternative route for the synthesis of aliphatic polyesters and offers various advantages compared with the conventional, metal-catalyzed polymerization reactions. Previous studies indicated that lipase-catalyzed polycondensation reactions between diols and diacids occurred preferentially at primary hydroxyl groups of diols, when diols contained both primary and secondary hydroxyl groups. In this work, we investigated lipase-catalyzed polycondensation of diacids and secondary hydroxyl group–containing diols, and successfully synthesized polyesters by polycondensation with secondary hydroxyl groups as well as primary hydroxyl groups. Various diols, glycerol, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, and 2,4-pentanediol were tested for the polycondensation. The polymerization was achieved by heating a mixture of lipase B, sebacic acid, and the diols in anhydrous toluene at 100 °C for 72 h. The resulting polymers were characterized by ¹H and ¹³C NMR spectroscopy, Fourier transform–infrared spectroscopy, thermogravimetric analysis, and gel permeation chromatography.     

近红外光谱法定量分析维生素E

在９３％～９７．４％浓度范围内,利用维生素Ｅ（ＶＥ）在６０６１～５２４６ｃｍ＾－１处的近红外吸收峰面积积分值和其浓度关系建立的回归方程为：Ｙ＝１０３．４３～０．０７８６２４Ｘ。用此回归方程对已知浓度的样品进行预测,误差及相对误并均在－０．７９％～０．９％内。在较宽浓度范围８０％～９７％之间的ＶＥ,用ＰＬＳ算法选择不同遥数据预处理方法,对近红外吸光度值和其含量的关系建模,度用已知浓度的ＶＥ进行校验。     

15-羟基十五烷酸的脂肪酶催化合成环十五内酯

15-羟基十五烷酸的脂肪酶催化合成环十五内酯     

维生素E与磷脂酰胆碱的单分子膜研究

测定了下列气水界面单分子膜的表面压－平均分子面积等温线：（１）ｄ－α，ｄ－β，ｄ－γ－，和ｄ－δ－生育酚等４种维生素Ｅ与ＤＰＰＣ，ＤＯＰＣ及ＤＬＰＣ的混合物，（２）ｄ－α－生育酚等摩尔比的ＤＰＰＣ和ＤＬＰＣ的混合物，（３）胆固醇与ＤＰＰＣ，ＤＬＰＣ的混合物，讨论了维生素Ｅ色满环上甲基对其在ＰＣ单分子膜中物理化作用的影响，实验结果表明：（１）维生素Ｅ以ｄ－α〉ｄ－β－≈ｄ－γ〉ｄ－δ的次序引起的ＤＰ