无溶剂体系脂肪酶动力学拆分2-辛醇及产物的非均相共沸蒸馏提取

为了提高脂肪酶在非水相中对手性仲醇的拆分效率,以2-辛醇为模式底物,建立了以辛酸为酰基供体的无溶剂脂肪酶动力学拆分手性仲醇的反应体系,采用1.5∶1的酸醇摩尔比,45℃条件下反应12 h,2-辛醇的转化率达到49.9%,并且S-2-辛醇的对映体过量率e.e.s=98.2%,反应的对映体比率E600。利用脂肪族仲醇与水形成共沸物的特性,通过非均相共沸蒸馏的方法提取拆分得到的手性仲醇,S-2-辛醇的光学纯度并未降低,并且产率大于90%,产品纯度大于98%。     

南方红豆杉叶精油化学成分的研究

采用水蒸汽蒸馏法提取南方红豆杉叶的精油,通过色谱－质谱－计算机联用技术分析了精油的化学成分。从中初步鉴定出２６个化合物,占精油总量的９６％,主要成分是：棕榈酸（３５．６６％）,９－十六碳烯酸９－十六碳稀酯（１１．２８％）,３－辛醇（４．４７％）,１－苯－１,２－丙二酮（４．３％）,Ｎ－苯基－１－萘胺（３．５７％）,１,２－苯二羧酸（２－甲基丙基）二酯（３．５７％）,６,１０－二甲基－５,９－十一双     

蓖麻油微波裂解制备癸二酸的研究--溶剂法

本文报道了以蓖麻油为原料在有机溶剂条件下经微波裂解法制备癸二酸的工艺条件研究。最佳工艺条件是，碱：２－辛醇：蓖麻油为１．５：２．１，ＮａＯＨ浓度５５．６％，微波功率１６０ｗ，裂解时间２０ｍｉｎ，癸二酸的产率达９２％。与传统方法比较，反应时间缩短３０多倍，节约了设备投资和能耗，减少了污染，降低了成本。     

白细胞介素2的中枢作用

白细胞介素２（ＩＬ－２）不仅是重要的免疫调节因子,而且具有重要的中枢调节作用。业已证实,脑内存在着ＩＬ－２和ＩＬ－２受体（ＩＬ－２Ｒ）,ＩＬ－２能明显地影响神经元和神经胶质细胞的生长,并能作用于下丘脑－垂体－肾上腺轴而影响内分泌,还能对电生理、行为等产生影响。本文简述了ＩＬ－２的中枢作用。     

D－氨基酸广泛存在于生命物质中──关于生物分子手性研究发展的评述

Ｄ－氨基酸广泛存在于生命物质中──关于生物分子手性研究发展的评述赵南生（北京天文馆,北京１０００４４）关键词Ｄ－氨基酸,Ｄ－氨基酸氧化酶,生物分子手性１９２４年化学家Ｋ．Ｆｒｅｎｄｅｎｂｅｒｇ将Ｌ－氨基酸冠以＂天然＂,而Ｄ－氨基酸就成了＂非天然＂,类...     

心血管疾病患者血清sIL—2R变化及其临床意义

白细胞介素２受体（ｉｎｔｅｒｌｅｕｋｉｎ－２ｒｅｃｅｐｔｏｒ,ＩＬ－２Ｒ）在白细胞介素２（ＩＬ－２）介导的免疫反应中起重要作用,目前它已成为国内外免疫学领域研究的热点之一,可溶性ＩＬ－２Ｒ（ｓＩＬ－２Ｒ）是ＩＬ－２Ｒ家族的另一成员,它来源于细胞膜低亲...     

脂肪酶活性和选择性受溶剂不同物化参数控制

采用假单胞菌脂肪酶在不同溶剂中催化辛酸与外消旋２－辛醇间的不对称酯合成反应时发现,酶的催化活性和对映选择性分别受溶剂不同物化参数的影响。前乾与溶剂疏水性有较发孤相关关系;而后者与介电常数和偶极矩关联较好。通过反动力学研究和由此提出孤脂麦活性中心结构模型对上述现象作了合理的解释。     

手性高效液相色谱法测定S（＋）—布洛芬对映体过量

用手性固定相高效液相色谱法测定了样品或样品或微生物酶不对称水解反应液中Ｓ（＋）－布洛芬对映体过量。该法首先将布洛芬转化为二苯酰胺衍生物,然后在Ｎ－３,５－二硝基苯甲酰－（Ｒ）－苯甘氨酸［（Ｒ）－ＤＮＢ－ＰＧ］的共价型ＣＳＰ柱上进行对映体ＨＰＬＣ分离。流动相选择正已烷－异丙醇（９８：２）,流速１ｍｌ／ｍｉｎ,对映体分离度１．４７。按相同方法同时进行消旋布洛芬的二苯酰胺衍生物的分离,由其对映体峰高比可     

白细胞介素2新的功能位点及其中枢镇痛作用

白细胞介素２（ＩＬ－２）,不仅是重要的免疫调节因子,而且具有重要的中枢调节作用。本工作表明：（１）ＩＬ－２具有中枢镇痛作用;（２）ＩＬ－２除具有免疫调节作用功能位点外,还存在着另一新的与之相互独立的镇痛功能位点;（３）ＩＬ－２的中枢镇痛作用,主要是由ＩＬ－２第４５位Ｔｙｒ残基以及空间结构上邻近的４４、１１７位Ｐｈｅ等残基共同构成的镇痛功能位点与阿片受体直接结合所介导。本工作提示,细胞因子的多功能性,可能是其相互独立的功能位点作用于不同的受体或受体亚型所致。     

白介素-2受体及其介导的信号转导

白介素２（ＩＬ－２）是一种重要的调控免疫系统细胞增殖和分化的细胞因子。其生物活性的发挥是通过与细胞表面白介素－２受体（ＩＬ－２Ｒ）结合,继而激活胞质内多种非受体型蛋白质酪氨酸激酶（ＰＴＫ）,进一步启动３种主要信号转导途径：控制基因转录的Ｊａｋ－ＳＴＡ...     

有机相中脂肪酶催化不对称酯合成反应动力学的研究

有机相中脂肪酶催化不对称酯合成反应动力学的研究杨红,高修功,郭妮妮,曹淑桂,杨同书（吉林大学酶工程国家重点实验室,长春１３００２３）在环已烷中应用酵母脂肪酶催化外消旋２－辛醇和辛酸的不对称酯合成反应,研究了该反应的动力学机制,测定了表现动力学常数．利...     

Esterification in Organic Media for Preparation of Optically Active Secondary Alcohols: Effects of Reaction Conditions

Esterification in an organic solvent for enantioselective preparation of optically active secondary alcohols was investigated using porcine pancreas lipase (PPL), (R,S)-2-octanol and dodecanoic acid in heptane. The influence of different reaction conditions on esterification rate and enantioselectivity was studied. Removal of water and immobilization of PPL both led to distinct improvement of the extent of ester formation and enantioselectivity of catalysis. Studies allowing continuous control of optical enrichment in the product (ester) and the remaining substrate (alcohol) were carried out in order to further optimize the reaction conditions. Optically pure (R)-and (S)-2-octanol were prepared.     

Effects of the Reaction Conditions on the Enantio-Selective Esterification Using Candiada Cylindracea Lipase

Parameters influencing the synthetic activity and enantioselectivlty of the Candida cylindracea lipase were investigated. The test reaction was presented through the enantioselective esterification of 2—substituted propionic acids in organic solvents. It was found that both the activity and the enantioselectivity of the lipase could be most effectively influenced by solvent engineering. Since the solvent has a different effect on activity and enantioselectivity of the lipase, selection of the most suitable solvent or solvent mixture is an important optimization question.     

复合诱变选育高产脂肪酶黑曲霉菌株及其固定化酶性质

通过硫酸二乙酯(DES)和微波复合诱变,获得遗传性状稳定的高产脂肪酶黑曲霉突变菌株CM2,酶活达174.93 U/mL.对菌株CM2培养条件的优化,以橄榄油和(NH_4)_2SO_4为最佳碳、氮源,在28℃、pH 7.5的条件下,发酵CM2菌株68 h,脂肪酶活为180.52 U/mL.大孔树脂固定化脂肪酶在35～55℃和pH 7.5～9.5之间有很好的稳定性.游离酶和固定化酶的表观失活活化能分别为52.6842 kJ/mol和30.8391 kJ/mol,固定化酶对温度的敏感度降低,耐受性增强.在微水相中脂肪酶催化2-辛醇和乙酸乙烯酯不对称酯交换反应中,(S)-乙酸辛酯的对映选择性高(游离酶e.e.s 85.7%;固定化酶e.e.s 87.7%),显示了该固定化酶在2-辛醇的手性拆分方面具有良好的应用前景.     

改性壳聚糖固定化脂肪酶的研究

以化学改性后的壳聚糖为载体固定假丝酵母99-125脂肪酶,研究了不同的活化剂对壳聚糖表面羟基基团的活化程度,及以活化后壳聚糖为载体采用不同固定化方法对假丝酵母脂肪酶固定效果的影响。结果表明1-乙基-3-(3-甲基氨基)丙基碳二亚胺可有效的活化壳聚糖表面羟基,活化后的壳聚糖表面氨基与戊二醛偶联后形成的壳聚糖为良好的脂肪酶固定化载体,其固定脂肪酶的水解活力可高达86.8U/g。此外,还对影响固定化进程中的各种因素进行了研究,确定最优条件,比较了固定化前后酶的热稳定性、有机溶剂稳定性及最适反应温度。并考察了该固定化脂肪酶催化合成棕榈酸十六酯的操作稳定性,结果表明,连续反应16批之后棕榈酸十六酯的转化率仍能达到85%以上。     

Lipase catalyzed esterification of lactic acid

Reactions between lactic acid and alcohols or carboxylic acids catalyzed by lipase from Candida antarctica were evaluated with hexane as solvent. Lactic acid was a good acyl donor and esters of both primary and secondary alcohols were effectively synthesized. No interfering dimer formation due to lactic acid acting as both nucleophile and acyl donor was observed. In agreement with this, no esterification occurred between lactic acid and carboxylic acids.     

脂肪酶在微乳液和微乳液凝胶中催化辛酸辛醇的酯化反应

脂肪酶在合成反应中具有很高的区域选择性和立体选择性 ,已广泛用于食品工业和药物工业[1,2 ] ,在有机介质中的脂肪酶催化反应已有较多研究[3 ,4 ] 。微乳液一般由表面活性剂、助表面活性剂、油和水等组份组成 ,它是一种热力学稳定、光学透明、宏观均匀而微观不均匀的体系 ,能提供酶催化所需要的巨大油 /水界面[5] 。而将脂肪酶增溶于油包水(Ｗ /Ｏ)微乳液中的纳米级“水池”中 ,可使酶以分子水平分散[6] ,图 1(ａ) ,从而可用来模拟细胞微环境中的反应。油包水微乳液中的酶可通过加入明胶而制成固定化酶 ,含明胶的微乳液凝胶 (ＭＢＧｓ)最早…     

Lipase catalyzed esterification of glycidol in organic solvents

We studied the resolution of racemic glycidol through esterification with butyric acid catalyzed by porcine pancreatic lipase in organic media. A screening of seven solvents (log P values between 0.49 and 3.0, P being the n-octanol-water partition coefficient of the solvent) showed that neither log P nor the logarithm of the molar solubility of water in the solvent provides good correlations between enantioselectivity and the properties of the organic media. Chloroform was one of the best solvents as regards the enantiomeric purity (e. p.) of the ester produced. In this solvent, the optimum temperature for the reaction was determined to be 35 degrees C. The enzyme exhibited maximum activity at a water content of 13 +/- 2% (w/w). The enantiomeric purity obtained was 83 +/- 2% of (S)-glycidyl butyrate and did not depend on the alcohol concentration or the enzyme water content for values of these parameters up to 200 mM and 25% (w/w), respectively. The reaction was found to follow a BiBi mechanism. (c) 1993 John Wiley & Sons, Inc.     

Enantioselective synthesis of ibuprofen esters in AOT/isooctane microemulsions by Candida cylindracea lipase

The enantioselective esterification of racemic ibuprofen, catalyzed by a Candida cylindracea lipase, was studied in a water-in-oil microemulsion (AOT/isooctane). By using n-propanol as the alcohol, an optimal W(0) ([H(2)O]/[AOT] ratio) of 12 was found for the synthesis of n-propyl-ibuprofenate at room temperature. The lipase showed high preference for the S(+)-enantiomer of ibuprofen, which was esterified to the corresponding S(+)-ibuprofen ester. The R(-)-ibuprofen remained unesterified in the microemulsion. The calculated enantioselectivity value (E) for S-ibuprofen ester was greater than 150 (conversion 0.32). The enzyme activities of n-alcohols with different chain lengths (3-12) were compared, and it appeared that short- (propanol and butanol) and long-chained (decanol and dodecanol) alcohols were better substrates than the intermediate ones (pentanol, hexanol, and octanol). However, unlike secondary and tertiary alcohols, all of the tested primary alcohols were substrates for the lipase. The reversible reaction (i.e., the hydrolysis of racemic ibuprofen ester in the microemulsion) was also carried out enantioselectively by the enzyme. Only the S form of the ester was hydrolyzed to the corresponding S-ibuprofen. The reaction yield was, however, only about 4% after 10 days of reaction. The corresponding yield for the esterification of ibuprofen was about 35% (10 days). The high enantioselectivity displayed by the lipase in the microemulsion system was seen neither in a similar esterification reaction in a pure organic solvent system (isooctane) nor in the hydrolysis reaction in an aqueous system (buffer). The E value for S-ibuprofen ester in the isooctane system was 3.0 (conversion 0.41), and only 1.3 for S-ibuprofen in the hydrolysis reaction (conversion 0.32). The differences in enantioselectivity for the lipase in various systems are likely due to interfacial phenomena. In the microemulsion system, the water in which the enzyme is dissolved is separated from the solvent by a layer of surfactant molecules, thus creating an interface with a relatively large area. Such interfaces are not present in the pure organic solvent systems (no surfactant) nor in aqueous systems. (c) 1993 John Wiley & Sons, Inc.     

糖脂修饰的脂肪酶在有机溶剂中催化酯化反应

本文研究了不同糖脂化合物修饰的脂肪酶在有机溶剂中催化长碳链脂肪酸和脂肪醇的酯化反应,不同的脂肪酶经糖脂修饰后,催化活性均有不同程度的提高。在４种糖脂和６种脂肪酶中,以蔗糖酯ＳＥ－７修饰脂肪酶ＣＥＳ活性最高,本文还对ｐＨ、溶剂和温度等对修饰脂肪酶生的影响进行了研究。