用壳聚糖修饰的大孔SiO_2材料固定化脂肪酶拆分萘普生甲酯

以壳聚糖(Chitosan,CS)修饰的大孔SiO_2材料为载体,通过吸附法固定柱状假丝酵母菌脂肪酶(Candida rugosa lipase,CRL)获得了CRL/CS-SiO_2固定化脂肪酶。并以催化拆分萘普生甲酯水解反应为对象,研究大孔SiO_2载体性能以及CRL固定量对反应的影响。结果表明,该CRL/CS-SiO_2固定化酶在结构上仍然保持载体Si O_2材料的微米级孔道,且CRL以纳米薄层的形式较为均匀地涂覆在孔道表面上。该固定化酶催化生成(S)-萘普生的转化率和选择性都远高于游离酶,其产物转化率随着CRL酶固定量的增加而增大,当CRL负载量为53.2 mg/g,反应120 h时,(S)-萘普生的转化率可达到44.6%,对映体过剩值eep达到100%,对映体选择性远大于200。     

Penicillium expansum脂肪酶选择性拆分外消旋萘普生

为了实现固定化扩展青霉TS414(Penicillium expansum TS414)脂肪酶在有机相中对外消旋萘普生的高效拆分,实验考察了水分、温度、有机溶剂、酶浓度、醇结构和醇浓度对酶促拆分反应的影响,确立了优化的酯化反应条件为：异辛烷为溶剂,外消旋萘普生2.15 mmol/L,正丙醇34.3 mmol/L,固定化酶量12 g/L,水0.05%(j), 40℃恒温摇床中200 r/min反应100 h. 在此条件下,酯化拆分反应的转化率为48.3%. 结果表明,固定化Penicillium expansum脂肪酶是一种较为理想的用于外消旋萘普生拆分的工具酶.     

利用分子印迹聚合物对外消旋药物萘普生的手性拆分

采用丙烯酰胺为功能单体,以二甲基丙烯酸乙二醇酯为交联剂,在模板分子(S)-萘普生的存在下,制备(S)-萘普生的分子印迹聚合物,并对其进行了高效液相色谱评价.结果表明,萘普生的外消旋混合物得到了较好的拆分,而且分离了与萘普生结构相似的布洛芬、酮洛芬,探讨了萘普生手性拆分的机理,考察了流速、流动相中乙酸含量对分离效果的影响.     

萘普生及其衍生物在CHIRALCEL OD-RH上的直接拆分

以酰氯化合物与萘普生反应制备系列萘普生衍生物,并对萘普生及其衍生物系列在CHIRALCEL OD-RH手性固定相(Chiral stationary phase,CSP)上的对映体直接拆分行为进行了研究.实验考察了流动相组成、流动相pH以及分离温度等因素对手性分离的影响.研究结果表明:萘普生及其系列衍生物的对映体在CHIRALCEL OD-RH手性固定相上均获得了直接拆分,较低的流动相pH条件以及较低的分离温度有利于对映体的分离,其最高对映体分离因子α值可达2.13,且分离因子α值与流动相组成关系曲线基本成线性,符合一般反相色谱分离的基本规律.     

基于β-环糊精/SiO_2手性固定相的薄层色谱法拆分DL-萘普生的研究

用β-环糊精(-βCD)键合硅胶合成了一种新型的β-环糊精/S iO2手性固定相,用红外对其进行了结构鉴定。将该手性固定相用于薄层色谱分离萘普生外消旋体,考察多种溶剂对萘普生外消旋体的展开效果,结果表明,乙酸乙酯∶氯仿(体积比)=1∶4为展开剂时,合成的手性固定相对DL-萘普生的分离度为1.45,具有很好的拆分DL-萘普生的能力。     

拟低共熔体系中脂肪酶水解拆分萘普生酯

引　言近年来已有许多用圆柱状假丝酵母脂肪酶(CCL)拆分消旋萘普生的报道[1～ 4 ] ,一般都是将底物萘普生酯完全溶解在有机溶剂中进行拆分反应 .然而有机溶剂的用量太大 ,不但对酶的催化活性有影响 ,而且还会带来安全和环保问题 .新发展的拟低共熔酶促反应体系恰能克服这一弊端     

(s)-萘普生丙炔醇酯的合成

以(s)—萘普生为原料,经二氯亚砜酰化为酰氯,与丙炔醇发生反应,合成萘普生丙炔醇酯,并用红外光谱、氢核磁共振谱对结构进行了表征。该方法反应条件温和,反应时问短,产率达82％。     

(S)-(+)-萘普生的催化不对称合成研究进展

对近10年来非甾体消炎镇痛药物(S)-(+)-萘普生的催化不对称合成方法进行了综述,重点介绍了不对称催化氢化反应、不对称氢氰化反应、不对称二羟基化反应和不对称交叉偶合反应等不对称合成技术的新进展.其中特别对不对称催化氢化反应中催化剂的高活性、高选择性以及分离回收方法的研究进展作了评述,指出了均相催化剂的多相化是今后的研究方向.同时提出了(S)-(+)-萘普生的催化不对称合成技术今后研究中需要解决的关键问题.     

有机相中固定化酶催化反应拆分手性化合物--间歇反应器内非定态动力学模拟

建立了有机相间歇反应器内球形多孔载体固定化酶催化反应拆分手性化合物的非定态动力学模型.采用正交配置法求解,讨论了对映体选择性E、内外传质阻力以及底物和水的抑制作用对酶促拆分手性化合物的拆分效果和速率的影响.结果表明:对映体选择性E是决定手性化合物能否拆分的关键参数;若一拆分过程对S-对映体优先反应,传质阻力可以忽略,E≥100,则R-和S-对映体几乎完全被拆分;如果存在传质阻力,则酶的对映体选择性降低,拆分效果不好,且拆分速率下降;底物和水的抑制作用对酶促拆分的效果影响不大,但拆分所需的时间相应增加.     

酶膜反应器的应用研究

介绍了酶膜反应器的基本概念,主要就酶膜反应器目前存在的突出问题和相应的解决方法进行了讨论,并对酶膜反应器的前景进行了展望。     

Dynamic enzymatic resolution of Naproxen methyl ester in a membrane bioreactor

A lipase‐catalyzed enantioselective continuous hydrolysis process under in situ racemization of substrate using sodium hydroxide as catalyst was developed for the production of (S)‐Naproxen from racemic Naproxen methyl ester in an aqueous–organic biphase system. Use of a tubular silicone rubber membrane in the stirred tank reactor to separate the chemical catalytic racemization and biocatalytic resolution processes, served to avoid the key problem associated with conventional dynamic resolution, viz the incompatibility of in situ chemical racemization with the presence of a biocatalyst. To overcome product inhibition and to facilitate product recovery from the aqueous–organic emulsion containing substrate and lipase, a hydrophilic porous semipermeable membrane was used in the stirred tank reactor. Greater than 60% conversion of the racemate with an enantiomeric excess of product (ee_p) greater than 96% was obtained. In addition, transformation of Candida rugosa lipase (CRL) isoenzymes was observed in the reaction process. © 2001 Society of Chemical Industry     

快速膜乳化法制备温敏微球及其固定胰蛋白酶

采用快速膜乳化法并结合低温聚合法制备了尺寸均一、重复性较好的聚(异丙基丙烯酰胺-丙烯酸) [P(NIPAM-co-AAc)]微球. 结果表明,所制微球平均粒径为5.2 mm,多分散性指数为0.0323. 对微球温敏响应性质的研究表明,加入亲水性单体会降低微球的低临界共溶解温度(LCST),且加入量越多LCST降低程度越大,交联剂加入量增大,微球的LCST升高. 加入亲水性共聚单体,微球的响应时间增加. P(NIPAM-co-AAc)微球用于胰蛋白酶固定化,在1-(3-二甲氨基丙基)-3-乙基碳二亚胺盐酸盐浓度0.9 mg/mL、胰蛋白酶浓度1.8 mg/mL及磷酸盐缓冲液浓度70 mmol/L时,可得到固载量为276 mg/g、活性回收率达75.07%的最优值,固定化胰蛋白酶的最适pH值为8、最适温度为37℃.     

A comprehensive study of the loss of enzyme activity in a continuous membrane reactor – application to starch hydrolysis

Loss of enzyme activity is a problem associated with enzymatic reactions in continuous recycled membrane reactors (CRMR). It may result from catalyst leakage and also enzyme denaturation due to the effects of pH, temperature, shear effects or adsorption/deposit on membrane. In this study, the relative importance of these various factors has been assessed in order to reduce their adverse effects on starch hydrolysis in a CRMR. The effects of temperature and denaturation by adsorption/deposit on membrane were the most limiting phenomena. Reducing the temperature to overcome thermal denaturation was not a practical solution since this increases viscosity and thereby decreases permeate flux and reactor performance. Insofar that adsorption/deposit of enzymes on the membrane is directly linked to membrane fouling, back‐flushing or regularly purging retentate should reduce this phenomenon by lowering accumulation of high molecular weight products. © 2001 Society of Chemical Industry     

动态膜分离式酶反应器连续操作运行方式评价与研究

应用动态膜分离技术开发研制的新型多功能酶反应器,实现了在进行酶解反应过程中同时分离产物的耦联操作。在该反应器上完成了使用菊粉酶、糖化酶等单基质酶不同操作形式的水解实验,考察了不同操作方式下反应器内流体流动的特性,并分别导出了停留时间分布函数式,从而对连续酶解过程的不同运行方式进行了对比性评价研究。     

Lipase‐catalyzed enantioselective esterification of S(+)‐naproxen ester prodrugs in cyclohexane

A lipase‐catalyzed enantioselective esterification process in cyclohexane was developed for the synthesis of S(+)‐naproxen ester prodrugs containing the moiety of N,N‐dialkylamino, ethylene glycol or alkyl ether of ethylene glycol. A high enantiomeric ratio of 44 was obtained when di(ethylene glycol) was selected as the best acyl acceptor. A reversible ping‐pong Bi Bi mechanism has been employed to elucidate the enzymatic behavior of the initial conversion rate for S(+)‐naproxen and the time‐course conversions for both enantiomers. Improvement of the enzyme activity was demonstrated when alcohol in excess of its cyclohexane solubility limit was used. The application of excess racemic naproxen in the presence of solid substrate suspensions showed enhanced productivity and enantioselectivity for the desired S(+)‐ester. Studies of the recovery and racemization of the remaining R(−)‐naproxen are also reported. © 1999 Society of Chemical Industry     

乳状液膜在湿法磷酸体系中稳定性的研究

研究了以N205为表面活性剂,磺酸基络合剂为流动载体,液体石蜡为膜增强剂,磺化煤油为膜溶剂,盐酸加氯化钠为内水相的乳状液膜在湿法磷酸体系中捕获镁离子时的稳定性。结果表明,表面活性剂用量、内水相反萃剂浓度、萃取时间、萃取转速等对液膜的稳定性均有显著影响。在一定的范围内,随着表面活性剂用量的增加,液膜的稳定性增加。适宜的操作条件为:在1 000 r/min下加内水相,3 000 r/min下制乳15 min,萃取转速为200 r/min。     

Removal of hydrogen sulphide from high salinity wastewater by emulsion liquid membrane

This article presents a experimental study on the removal of hydrogen sulphide (H₂S) from high salinity wastewater by emulsion liquid membrane (ELM). The ELM contains diethanolamine (DEA) as carrier, kerosene as solvent and span 80 as surfactant. The fundamental parameters (viz. surfactant concentration, carrier concentration, strip phase concentration, phase ratio, agitation speed and time) affecting the removal of H₂S were investigated to select the optimum combination of process parameters. The results showed the optimal governing parameters were: inner phase NaOH aqueous solution 2.0 wt%, Surfactant (span 80) 5.0 vol%, carrier (DEA) 6.0 vol%, treat ratio 1:5, agitation speed 250 rpm, agitation time 15 min, respectively, and removal efficiency of 97.3% was achieved. © 2011 Canadian Society for Chemical Engineering     

膜反应器包衣酶法水解橄榄油的研究

在聚丙烯腈中空纤维膜反应器油-水两相体系中,使用表面活性剂包衣酶催化水解橄榄油。含有橄榄油和包衣酶的油相(有机相)在中空纤维膜管束内循环流动,而在纤维膜管束外则是水相循环。实验表明橄榄油和油酸的截留率分别为91％和82％,包衣酶全部截留在管束内。在30℃、橄榄油浓度为0.62 mol/L时,包衣酶催化底物转化率为60％,是相应脂肪酶催化转化率的2倍。