Hydrolysis and esterification with immobilized lipase on hydrophobic and hydrophilic zeolites

Hydrolysis and esterification in a triolein/oleic acid system were compared with Candida cylindracea lipase attached to celite, hydrophobic zeolite and hydrophilic zeolite. The hydrophilic zeolite blocked the hydrolysis but mediated the esterification. Esterification with celite or hydrophobic zeolite as carrier was poor.     

Immobilisation of different Candida rugosa lipases by adsorption onto polypropylene powder: application to chiral synthesis of ibuprofen and trans‐2‐phenyl‐1‐cyclohexanol esters

Candida rugosa lipases (CRLs) were immobilised by adsorption onto a commercial polypropylene powder EP100?. Two commercial CRLs from Sigma and Amano were used together with two CRLs obtained by fed‐batch fermentation using oleic acid as a carbon source (UAB‐CRL). Significant differences were observed in the isotherm adsorption patterns for the commercial and fermented lipases, probably caused by differences in their polysaccharide content. The commercial lipases showed a classical Langmuir adsorption pattern, whereas fed‐batch produced lipases with high polysaccharide content tended to conform to a BET multilayer adsorption equation. Immobilised CRLs also showed different behaviour in the resolution of two interesting pharmaceutical products: ibuprofen and trans‐2‐phenyl‐1‐cyclohexanol (TPCH) in the enantioselective esterification reaction in organic media. In the case of ibuprofen, CRLs showed important differences in terms of esterification rate, probably due to diffusional limitation effects caused by the high polysaccharide content present in UAB‐CRLs. In the case of TPCH, however, polysaccharide content did not appear to influence the esterification rate. A high enantioselective esterification was observed for all CRLs tested in the resolution of both products. © 2002 Society of Chemical Industry     

Enzymatic synthesis of oleyl oleate in dense fluids

Esterification between oleic acid and oleyl alcohol, catalyzed by theMucor miehei immobilized lipase in a batch-stirred tank reactor with supercritical carbon dioxide as solvent produced higher reaction rates at supercritical conditions than in the solvent-free system. A continuous fixed-bed reactor was designed based on the results obtained from batch experiments. At 150 bar, 40°C, and with water activity 0.46% w/w, the activity of the enzyme preparation is practically unchanged when CO₂ was used as solvent. The addition of small amounts of water increases the conversion rate. The higher conversion also was observed at longer residence time. Whenn-butane was used as reaction medium, a decrease in conversion was observed.     

Transesterification of oil by fatty acid-modified lipase

Fatty acid was covalently attached to lipase (EC 3.1.1.3.) fromPhycomyces nites, yielding a modified lipase of higher specific activity in hydrolytic and synthetic reactions in organic solvents. Attached long-chain fatty acids solubilized the lipase in organic solvent and, therefore, promotion of dispersibility in organic solvent resulted in much higher reactivity. The initial rate of transesterification by modified lipase was almost 40 times that of native lipase in organic solvent. The specificities and selectivity of the modified lipase depended on the kind of attached fatty acid.     

The hydrolysis of phosphatidylcholine by an immobilized lipase: Optimization of hydrolysis in organic solvents

The ability of a commercial immobilized lipase preparation (Lipozyme) to hydrolyze the fatty acyl ester bonds of soybean phosphatidylcholine in organic media was investigated. Response surface methodology, based on a Modified Central Composite design, was employed to examine the effects on hydrolysis of solvent polarity, water, pH, duration and temperature of incubation, and the amounts of substrate and catalyst. A second-order regression model was developed, which allows evaluation of the effects of these parameters, alone or in combination. Hydrolysis increased in a relatively straightforward manner in response to increases in incubation time and the amount of catalyst and was approximately constant over the range of substrate amounts studied. Solvent polarity had a profound effect on the degree of hydrolysis, and the qualitative and quantitative degrees of this effect were dependent upon the values of the other parameters studied. Conditions were identified where enzyme activity was strong in either nonpolar or polar solvents, with activity increasing as the polarity of the medium increased. Enzyme activity was minimum at about 37°C, increasing below and above this temperature. Activity was not affected by the presence of acid or base in the reactions. Increasing amounts of water stimulated enzyme activity in solvents more polar than hexane, while in less polar solvents water inhibited activity.     

微生物脂肪酶的应用领域及研究进展

随着工业催化技术的发展,脂肪酶作为一种重要的生物催化剂现已成为世界研究的热点.对微生物脂肪酶的结构、性质以及在粮油食品加工、生物柴油、有机合成、手性化合物合成及三甘酯结构测定等方面的应用进行了综述和展望.     

基于酶促聚合反应的棉织物疏水改性工艺优化

为改善棉织物的疏水性能,选取酶浓度、温度和处理时间3个影响因素,以静态接触角为评价指标,采用三因素三水平正交试验方法,对基于脂肪酶催化聚合反应的棉织物疏水改性工艺进行优化,结果表明,最优工艺条件为处理时间9 h,温度45℃,酶浓度45%(体积分数),此时棉织物的静态接触角为119.58°,润湿时间达109 s。扫描电镜结果表明改性后棉织物的纤维表面被许多颗粒覆盖。采用基质辅助激光解吸电离飞行时间质谱测试仪,对改性棉织物的纤维素酶水解液进行化学表征,结果表明,在改性后棉织物的纤维素酶水解液中,存在脂肪酶催化合成的聚酯低聚物,最高聚合度为7,具有不同种类端基的聚酯分子的平均聚合度分别为3.27(nCA)、5.26(nCC)、5.66(nAA)。综合物理性能表征及化学表征分析,揭示了脂肪酶催化双酯类单体戊二酸二乙酯与乙二醇二乙酸酯在棉织物表面聚合对棉织物进行疏水改性的作用机制:在棉织物表面酶促生成的疏水性聚酯低聚物分子紧密附着或嵌合在棉织物纤维集合体之间,在其表面形成一薄层疏水防护层,赋予棉织物良好的疏水性能。