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。     

聚甲基丙烯酸羟乙酯载体固定化酵母脂肪酶在有机溶剂中催化…

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。     

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.     

聚丙烯酸甲酯载体对柱状假丝酵母脂肪酶固定化的研究（Ⅰ）

合成了一系列不同结构的聚丙烯酸甲酯，考察了它们的固定化酵母脂肪酶催化酯水解反应的效果，得到了载体孔结构对固定化效果影响的一些规律．研究了最佳吸附条件，比较ｐＨ和离子强度对酵母脂肪酶自由酶和固定化酶催化酯水解反应活力的影响．     

无溶剂体系脂肪酶催化合成阿魏酸油醇酯

对无溶剂体系中阿魏酸的转酯化疏水改性进行了研究,确立了减压反应器(0.001 MPa)中Novozym 435脂肪酶催化阿魏酸乙酯和油醇进行转酯化反应合成新型抗氧化剂阿魏酸油醇酯的方法.发现水活度(aw)明显影响转酯反应,阿魏酸油醇酯产率在aw＜0.01-0.75范围内随着水活度的增加而降低,推测底物阿魏酸乙酯和产物阿...     

无溶剂体系酶促阿魏酸双甘酯合成的研究

对酶催化合成阿魏酸双甘酯的脂肪酶进了筛选和比较,并对影响合成阿魏酸双甘酯的因素(助溶剂、转速、底物比、时间、温度、水含量和硅藻土添加量)进行了探讨,结果表明无溶剂反应体系中阿魏酸双甘酯的产率远远高于含有助溶剂体系中反应.同时优化了反应条:无溶剂体系中在70mg CRL催化下,转速为150 r/m in,底物比为1:1,反应时间为120 h,水含量为10 ug/g,硅藻土添加量为40 mg时产率可达33.25%.     

非水介质中脂肪酶催化亚麻酸油醇酯合成的研究

已知脂肪酶（ＥＣ３．１．１．３）在非水体系中能够催化合成脂肪族、芳香族和其它多种多样的酯类．这些反应中的大多数都是以链较长的脂肪酸为底物．其中一类反应是高级脂肪酸和脂肪醇合成酯蜡的酯化反应．合成的酯蜡用途广泛,可以用在化工、纺织、医药、日化、食品等工业中．利用传统的化学法合成酯蜡,需要在高温高压及强酸条件下进行反应,副反应多,产物的分离纯化困难,生产成本高,且对于长链脂肪酸和醇的反应难度增大．利用脂肪酶水解反应的逆反应酯化反应合成酯蜡的方法,具有反应条件温和,产物的分离纯化容易等优点,能够弥补化…     

脂肪酶直接与硅胶混合催化无溶剂酯化反应的研究

用硅胶作为载体，以癸酸与己醇的酯化反应作为模型，将脂肪酶和底物直接与硅胶混合，用于无溶剂体系催化酯化反应．结果表明体系中水的含量、底物用量比以及反应时间均对酯化反应有较大影响．在该体系中，脂肪酶催化酯合成反应的速度显著增加，反应2h后．转化率可以达到90％以上．而且沉积在硅胶上的脂肪酶可以反复使用多次．     

固定化米曲霉催化拆分丙氨酸消旋体的反应特性

研究了溶液ｐＨ、搅拌强度，催化剂用量、底物浓度及产物浓度对固定化米曲霉催化拆分Ｎ－乙酰－ＤＬ－丙氨酸反应的影响。结果表明，低底物浓度（Ｓ〈０．２ｍｏｌ／Ｌ）时反应符合Ｍ－Ｍ方程，底物浓度Ｓ〉０．２ｍｏｌ／Ｌ时，有底物抑制现象，当产物浓度Ｐ〉１０ｍｍｏｌ／Ｌ时反应存在产物抑制现象。     

华根霉脂肪酶有机相酯合成活性的重塑

研究了具有较高酯合成活性的华根霉膜相关脂肪酶及其沉淀酶蛋白的重折叠处理过程, 发现膜成分及表面活性剂可能是影响其活性的关键因素. 进一步考察了影响异源表达的可溶性华根霉脂肪酶r27RCL酯合成活性重塑的关键因子及作用阶段. 研究结果表明, 表面活性剂对脂肪酶的酯合成活性具有关键影响, 直接添加表面活性剂可使酯合成活性显著提高. 在7种不同表面活性剂中, 两性离子表面活性剂LPC14将r27RCL的酯合成活性提高了5.75倍. 分子动力学模拟结果表明, 在有机相反应中, 表面活性剂的添加使脂肪酶催化三联体之间的氢键作用力得到加强, 从而提高了脂肪酶的有机相酯合成能力.     

The effect of monosaccharides on self-assembly of benzenetricarboxamides

In this work, three common monosaccharides, glucose, galactose and mannose, are employed to investigate the effect of monosaccharide on the self-assembly of benzenetricarboxamide (BTA) core-containing molecules. Based on the effect of monosaccharides, three benzenetricarboxamide derivatives aggregate into different ordered structures, i.e., vesicles, nanorings and fibers. When alanine linkers are introduced to these molecules between the core and the monosacchride, all monosaccharide-based BTAs aggregate into irregular morphologies, meanwhile they become similar with the increase of the length of alanine linkers indicating the disappearance of the monosaccharide effects.     

有机溶剂中脂肪酶催化酯交换反应的研究

对几种有机溶剂中猪胰脂肪酸催化的酯交换反应进行了研究，详细考察了反应温度、反应时间、反应物摩尔比、反应物中水含量和不同溶剂对反应性能的影响。结果表明：1．反应温度在313K左右时酶显示出最高催化活性。2．在实验条件下，反应进行72h后，转化率不再随反应时间的延长而变化，即反应达到平衡。3．酯／醇摩尔比的增大对反应转化率的影响较小。4．反应系统中水含量为0．5％－1．3％时，酶的催化活性最高。5．酶的催化活性随溶剂极性增大而降低。     

脂肪酶在有机溶剂中催化酯合成和酯交换反应

报道了猪胰脂肪酶在冻干时的pH值、有机溶剂的极性、反应系统的含水量、温度以及底物碳链的长度和支链对酶在有机相中催化活性的影响规律。利用该酶合成了具有玫瑰香味的月桂酸香茅酯和辛酸香茅酯。     

Chemoenzymatic dynamic kinetic resolution of acyloins

[Reaction: see text]. Acyloins (alpha-hydroxy ketones) are important building blocks in organic synthesis, e.g., for the total synthesis of epothilones. Optically pure acyloins can be obtained by lipase-catalyzed kinetic resolution (KR) of the racemate with, for example, Burkholderia cepacia lipase, but this process suffers from a yield limitation of 50%. To devise a dynamic kinetic resolution (DKR), we studied the racemization of two different acyloins and corresponding esters with various amine bases and ion exchangers. No combination of base and solvent was found that could selectively racemize the acyloin or corresponding ester under the conditions needed for a DKR. In contrast to bases, acidic resins (ARs) were found to racemize the acyloins selectively in n-hexane and in water. Unfortunately, the AR deactivated the lipase, preventing a one-pot DKR. Minor side reactions involving the AR, the substrate acyloin, and the vinyl ester acyl donor were also observed. However, an efficient DKR was made possible by the spatial separation of lipase and ion exchanger, with enzymatic transesterification and AR-catalyzed racemization taking place simultaneously in two compartments connected by a pump loop. The conversion of substrate alcohol was 91%, the selectivity toward the product butyrate ester 90%, and the enantiomeric excess of the (S)-product 93% ee.     

Enzymatic resolution of (RS)-β-hydroxy selenides in organic media

Kinetic resolutions of a number of β-hydroxy selenides promoted by enzymes were performed using PPL (free Porcine pancreatic lipase), PSL (Amano PS—free Pseudomonas sp. lipase) and CALB (NOVOZYM 435^®—immobilized Candida Antarctica lipase type B) with (RS)-1-phenylselanyl-propan-2-ol. CALB gave the best results and provided both (R)- and (S)-enantiomers in high enantiomeric purity. A comparative study of the effect of temperature, solvent, enzyme immobilization and the structure of the substrates on the resolution is presented.     

Fragrance release from the surface of branched poly (amide)s

Enzymes are powerful tools in organic synthesis that are able to catalyse a wide variety of selective chemical transformations under mild and environmentally friendly conditions. Enzymes such as the lipases have also found applications in the synthesis and degradation of polymeric materials. However, the use of these natural catalysts in the synthesis and the post-synthetic modification of dendrimers and hyperbranched molecules is an application of chemistry yet to be explored extensively. In this study the use of two hydrolytic enzymes, a lipase from Candida cylindracea and a cutinase from Fusarium solani pisii, were investigated in the selective cleavage of ester groups situated on the peripheral layer of two families of branched polyamides. These branched polyamides were conjugated to simple fragrances citronellol and L-menthol via ester linkages. Hydrolysis of the ester linkage between the fragrances and the branched polyamide support was carried out in aqueous buffered systems at slightly basic pH values under the optimum operative conditions for the enzymes used. These preliminary qualitative investigations revealed that partial cleavage of the ester functionalities from the branched polyamide support had occurred. However, the ability of the enzymes to interact with the substrates decreased considerably as the branching density, the rigidity of the structure and the bulkiness of the polyamide-fragrance conjugates increased.     

脂肪酶催化一步酯化协同拆分合成S-萘普生淀粉酯前药

利用CRL脂肪酶选择性催化外消旋萘普生甲酯与玉米淀粉进行转酯化反应合成光学纯S-萘普生淀粉酯前药,同时达到拆分外消旋萘普生的目的。考察了有机溶剂、脂肪酶用量、底物浓度比、反应温度对酯化协同拆分反应的影响,结果表明在异辛烷中脂肪酶CRL可以催化S-萘普生甲酯与淀粉发生转酯化反应同时完成外消旋萘普生的拆分,并且在脂肪酶用量为10%、底物浓度比为1:3、异辛烷用量为15mL、反应温度为60℃的条件下反应6d,外消旋萘普生甲酯的转化率为27.2%,产物对应体过量值eep高达99.4%可以作为萘普生的前药进行应用。