硝基苯和乙醇一锅法合成N-乙基苯胺

以硝基苯和乙醇一锅法合成N-乙基苯胺为例,报道了芳香硝基物和醇类化合物在一个反应器内,在相同催化剂作用下和在相同反应条件下一锅法合成N-烷基芳胺的新方法.在该方法中,醇类化合物水相重整过程中产生的氢原位地将芳香硝基物加氢还原生成芳胺,紧接着在较低的H2分压条件下,芳胺与醇发生N-烷基化反应生成相应的N-烷基芳胺.在硝基苯：无水乙醇：水的体积比为10：60：0时,在T=413K和P=1MPa条件下反应8h,硝基苯和苯胺被完全转化,N-乙基苯胺的选择性为85.9％,N,N-二乙基苯胺选择性在0-4％之间,明显优于传统的合成方法。实验结果表明,这种方法可及时地将反应过程产生的氢和芳胺从催化剂表面移走,为提高目标产物N-烷基芳胺的选择性提供了可能。     

改进的Ugi法应用于胺烷基二茂铁衍生物的合成

选择不同的按或酰胺组分, 利用改进的Ugi法合成了一系歹含有烷胺烷基、芳胺烷基或酰胺烷基的二茂铁衍生物, 研究了反应的投料比, 反应底物, 反应温域等因素对反应的影响, 并对反应机理进行了探讨。     

漆树酶的固定化研究

本文对我国特产资源生漆液中漆树酶的固定化进行了研究。考查了各种无机盐溶液处理不同无机载体,活化反应及漆树酶固定化条件对固定化漆树酶性能的影响。研究表明,经ZrCl_4处理后的多孔硅胶作载体的固定化漆树酶活力回收高、稳定性好、重复使用20次其保留活力仍有75%。同时对固定化漆树酶和自由态漆树酶的反应pH、温度、K_m值作了比较。对漆树酶通过过渡金属氢氧化物固定在无机载体土的机理也作了初步探讨。     

非水介质中分酚氧化酶催经羟基化反应的研究

以对甲酚为底物,利用双马铃薯中提取的多酚氧化酶的粗酶液,用多孔玻璃包衣琼脂疏水吸附法将多酚氧化酶固定化,并利用此固定化酶,考察了在非水介质中羟基化反应的最适宜条件,在此条件下催化合成4－甲基邻苯二酚的产率为55．8％。     

大孔载体对米曲霉氨基酰化酶的固定化研究

用合成的大孔丙烯酸甲酯-—二乙烯苯交联共聚物(聚丙烯酸甲酯)、丙烯酰胺-N,N′-亚甲基双丙烯酰胺交联共聚物(聚丙烯酰胺)及它们的功能基化产物作为固定化氨基酰化酶的载体。考察了载体性质对固定化氨基酰化酶效果的影响。比较了底物浓度、pH、磷酸缓冲液浓度、温度对氨基酰化酶溶液酶及固定化酶的影响。利用其中一种载体制成固定化酶柱,对DL-蛋氨酸进行了连续拆分,考察固定化酶的操作稳定性。     

固定化嗜热菌蛋白酶催化合成二肽甜味剂Aspartame

以氨丙基多孔硅球作载体,以戊二醛作交联剂制备的固定化嗜热菌蛋白酶催化合成Aspartame前体,通过酸化脱盐、氢化等反应得到二肽甜味剂Aspartame。研究了反应条件对合成Aspartame前体产率的影响,考察了固定化酶的重复使用性能。结果表明,固定化酶在水相中能较好的催化合成Aspartame前体,且具有良好的重复使用性能。     

N-甲基-N-芳基-2-(4''''-硝基苯硫基)乙酰胺类化合物的合成

先由芳胺合成 N-甲基芳胺 ,再由氯乙酰氯酰化后与对硝基硫酚在相转移催化条件下反应 ,生成 2 -(4 -硝基苯硫基 )乙酰芳胺。该法具有操作简便 ,产率高的优点。     

N-甲基-N-芳基-2-(4＇-硝基苯硫基)乙酰胺类化合物的合成

先由芳胺合成N-甲基芳胺,再由氯乙酰氯酰化后与对硝基硫酚在相转移催化条件下反应,生成2-(4＇-硝基苯硫基)乙酰芳胺.该法具有操作简便,产率高的优点.     

载体对包埋酶微环境的影响分析

包埋法固定化酶过程中,酶固定化载体的选择和设计是酶固定化过程的关键因素,适宜的载体微环境对酶活性和稳定性的影响尤为重要。论文首先分析并提出了影响固定化酶所处载体微环境的主要因素,包括载体的亲疏水性、结构形态和反应活性。载体的亲疏水性决定固定化酶微环境中的水分含量。载体的结构形态对酶形成的笼效应,以及载体的反应活性,包括共价键合、静电和氢键等的结合能力,影响酶构象的稳定性和运动性。另外,底物／产物的扩散速率和酶的可及性也同样受到载体的孔结构、孔分布以及载体反应活性的影响。本文介绍了常用的酶包埋载体,包括sol-gel二氧化硅、高分子水凝胶以及高分子－二氧化硅杂化凝胶固定化酶过程,结合上述影响酶微环境的因素,分析比较了三类载体固定化酶的包埋率、活性和稳定性,综述了为改善固定化酶微环境所进行改进研究的进展。     

芳香胺参加的Mannich反应(Ⅱ)——用芳胺盐酸盐合成β-芳胺基酮

室温时芳香胺盐酸盐与甲醛、烷基芳基酮在HCl(气)-C₂H₅OH溶液中可以直接发生Mannich反应,生成β-芳胺基芳酮。这是继文献[1]之后,通过Mannich反应直接合成β-芳胺基芳酮的一个新方法。产率与文献[1]相近或略高。脂肪酮如丙酮、丁酮、甲基异丙基甲酮、甲基异丁基甲酮;环酮如环己酮、环庚酮,同样能发生上述反应。用HNMR谱测定了不对称酮与芳胺及甲醛进行Mannich反应所得到的β-芳胺基脂酮的结构。这一事实说明在室温及酸性条件下,可以用芳胺一步直接合成β-芳胺基酮,其反应机理仍符合一般公认的Mannich反应机理。     

固定化乙酰胆碱酯酶的制备及其特性研究

本研究以期研制出能重复使用的固定化乙酰胆碱酯酶(AChE),为天然产物复杂体系中AchE抑制剂筛选新方法的发展奠定基础.以氨基化硅胶(APS-Si)微球为载体,戊二醛为交联剂对乙酰胆碱酯酶进行交联固定化,并研究了酶的最佳固定化条件和固定化酶的性质.结果表明,0.05 g氨基化硅胶微球载体,用戊二醛溶液活化6 h后,在给酶量5 U,28℃固定16 h条件下,得到固定化酶的活性最大.固定化酶在常温(20～40℃),以及较宽pH范围内(pH 6～10)均具有较高的活性,并且具有良好的保存稳定性和可重复利用率,为基于固定化靶酶亲和-色谱质谱联用分析快速筛选乙酰胆碱酯酶抑制剂新方法的发展奠定了基础.     

Efficient Immobilization of Porcine Pancreatic α-Amylase on Amino-Functionalized Magnetite Nanoparticles: Characterization and Stability Evaluation of the Immobilized Enzyme

The potential of the modified magnetic nanoparticles for covalent immobilization of porcine pancreatic α-amylase has been investigated. The synthesis and immobilization processes were simple and fast. The co-precipitation method was used for synthesis of magnetic iron oxide (Fe₃O₄) nanoparticles (NPs) which were subsequently coated with silica through sol–gel reaction. The amino-functionalized NPs were prepared by treating silica-coated NPs with 3-aminopropyltriethoxysilane followed by covalent immobilization of α-amylase by glutaraldehyde. The optimum enzyme concentration and incubation time for immobilization reaction were 150 mg and 4 h, respectively. Upon this immobilization, the α-amylase retained more than 50 % of its initial specific activity. The optimum pH for maximal catalytic activity of the immobilized enzyme was 6.5 at 45 °C. The kinetic studies on the immobilized enzyme and its free counterpart revealed an acceptable change of K_m and V_max. The Km values were found as 4 and 2.5 mM for free and immobilized enzymes, respectively. The V_max values for the free and immobilized enzymes were calculated as 1.75 and 1.03 μmol mg^?1 min^?1, in order, when starch was used as the substrate. A quick separation of immobilized amylase from reaction mixture was achieved when a magnetically active support was applied. In comparison to the free enzyme, the immobilized enzyme was thermally stable and was reusable for 9 cycles while retaining 68 % of its initial activity.     

Influence of Silica-Derived Nano-Supporters on Cellobiase After Immobilization

Core shell magnetite nanoparticle (CSMN) was successfully synthesized with diameter around 125 nm according to the determination with scanning electronic microscopy. SBA-15 with diameter around 31 nm was synthesized in our previous work as another supporter for immobilized degradation enzymes. The aim of this study was to investigate the influence of silica-derived nano-supporters on cellobiase after immobilization. With covalent method, glutaraldehyde was introduced to immobilize cellobiase. The immobilized enzyme efficiency, specific activity, and its characterization, including optimum pH, pH stability, optimum temperature for enzyme reaction, and enzyme thermal stability were investigated. Results show that the method of enzyme immobilization on both nano-supporters could improve cellobiase stability under low pH and high temperature conditions compared with the free enzyme. In the aspect of immobilization efficiency, SBA had higher amount of bounded protein than that of CSMN, but had lower specific enzyme activity than CSMN, assumably due to the change in silica surface properties caused by process of supporter synthesis.     

Highly Efficient Method Towards In Situ Immobilization of Invertase Using Cryogelation

A novel method was developed for the immobilization of Saccharomyces cerevisiae invertase within supermacroporous polyacrylamide cryogel and was used to produce invert sugar. First, the cross-linking of invertase with soluble polyglutaraldehyde (PGA) was carried out prior to immobilization in order to increase the bulkiness of invertase and thus preventing the leakage of the cross-linked enzyme after immobilization by entrapment. And then, in situ immobilization of PGA cross-linked invertase within cryogel synthesis was achieved by free radical polymerization in semi-frozen state. The method resulted in 100 % immobilization and 74 % activity yields. The immobilized invertase retained all the initial activity for 30 days and 30 batch reactions. Immobilization had no effect on optimum temperature and it was 60 °C for both free and immobilized enzyme. However, optimum pH was affected upon immobilization. Optimum pH values for free and immobilized enzyme were 4.5 and 5.0, respectively. The immobilized enzyme was more stable than the free enzyme at high pH and temperatures. The kinetic parameters for free and immobilized invertase were also determined. The newly developed method is simple yet effective and could be used for the immobilization of some other enzymes and microorganisms.     

介孔分子筛SBA-15中α-胰凝乳蛋白酶组装及催化活性研究

介孔分子筛由于规则孔道或笼的存在 ,使其具有择形催化作用、高比表面积和强吸附性能 ,其孔道中可组装多种物质而改变其理化性能 .Thomas等 [1] 在介孔 Si O2 上接枝金属茂复合物 .白妮 [2 ] 和张雪峥 [3 ] 等分别将脂溶性金属酞菁衍生物和杂多酸封装在介孔分子筛中 ,得到的组装体催化性能优良 .近年来由于不断合成出 MCM- 41 [4 ] 和 SBA- 1 5 [5] 等孔径较大的介孔分子筛 ,使在介孔材料孔道中组装生物大分子成为可能 .Yen等 [6] 将细胞色素 c组装到孔道中 ,并使酶的稳定性得到提高 ,而α-胰凝乳蛋白酶 (Mr=2 5 0 0 0 ,分子动力学直径…     

疏水性聚丙烯酸/聚乙烯醇/葡萄糖淀粉酶复合纳米纤维膜的制备及酶学性质

利用混合静电纺丝将葡萄糖淀粉酶(GA)固定于聚丙烯酸(PAA)/聚乙烯醇(PVA)纳米纤维膜上,并通过鉴定固定化GA的酶学特征检验PAA/PVA可否成为一种优良的酶固定化载体。 对其理化性质和酶学特征进行鉴定,经红外光谱(FT-IR)和扫描电子显微镜(SEM)表征发现,GA可成功包埋于PAA/PVA纳米纤维膜内部;对包裹固定的GA进行酶学性质鉴定,发现固定化GA的最适反应温度为68 ℃,比游离GA提高了9 ℃;固定化GA的适用pH值范围明显变宽;热稳定性和存贮稳定性显著增强且可以重复使用。PAA/PVA纳米纤维膜是一种优良的酶固定化载体,可以通过混合静电纺丝包埋法简便地将蛋白质分子固定于其内部,具有一定的应用前景。     

Covalent immobilization of glucose oxidase onto new modified acrylonitrile copolymer/silica gel hybrid supports

New polymer/silica gel hybrid supports were prepared by coating high surface area of silica gel with modified acrylonitrile copolymer. The concentrations of the modifying agent (NaOH) and the modified polymer were varied. GOD was covalently immobilized on these hybrid supports and the relative activity and the amount of bound protein were determined. The highest relative activity and sufficient amount of bound protein of the immobilized GOD were achieved in 10% NaOH and 2% solution of modified acrylonitrile copolymer. The influence of glutaraldehyde concentration and the storage time on enzyme efficiency were examined. Glutaraldehyde concentration of 0.5% is optimal for the immobilized GOD. It was shown that the covalently bound enzyme (using 0.5% glutaraldehyde) had higher relative activity than the activity of the adsorbed enzyme. Covalently immobilized GOD with 0.5% glutaraldehyde was more stable for four months in comparison with the one immobilized on pure silica gel, hybrid support with 10% glutaraldehyde and the free enzyme. The effect of the pore size on the enzyme efficiency was studied on four types of silica gel with different pore size. Silica with large pores (CPC-Silica carrier, 375 A) presented higher relative activity than those with smaller pore size (Silica gel with 4, 40 and 100 A). The amount of bound protein was also reduced with decreasing the pore size. The effect of particle size was studied and it was found out that the smaller the particle size was, the greater the activity and the amount of immobilized enzyme were. The obtained results proved that these new polymer/silica gel hybrid supports were suitable for GOD immobilization.     

基于聚乙烯醇/Fe2O3纳米颗粒的纤维素酶固定化

以聚乙烯醇/Fe2O3磁性纳米颗粒为纤维素酶固定化载体, 通过反复冻融的方法成功地实现了纤维素酶固定化. 采用透射电镜、红外光谱仪、振动样品磁强度计对固定化酶复合体进行了表征, 结果显示, 固定化酶复合体为大小约1 μm的微凝胶团, 内含10 nm左右的Fe2O3纳米颗粒. 研究影响固定化因素后发现, 当pH为6, 固定化时间为11 h, 纤维素酶/PVA质量比为4, PVA/Fe质量比为50时, 固定化纤维素酶效果最好. 通过该方法固定后酶活回收率达42%, 酶水解效率显著提高, 经过5次反应后的固定化酶相对酶活力保留50%以上. 因此, 基于聚乙烯醇/Fe2O3纳米颗粒的纤维素酶固定有利于酶的循环使用并显著提高酶的使用效率, 是一种有效固定化纤维素酶的新方法.     

大孔阴离子树脂DEAE-E/H固定化氨基酰化酶的研究

以弱碱性大孔阴离子树脂DEAE-E/H为载体固定化氨基酰化酶.通过对影响固定化结果的几个因素,如树脂的离子类型、pH值、温度,以及自由酶液浓度等进行系统研究,得到了适宜的固定化条件:将DEAE-E/H转化为Ac-型;自由酶液浓度120U/ml,pH值6.5;固定化温度为常温.在此条件下制备的固定化氨基酰化酶比酶活可达1200U/g～1500U/g,酶活保留率超过60%.DEAE-E/H作为固定化载体,具有价格低廉,物理性能好,固定化方法简便等特点,具有很好的工业应用前景.     

Affinity Covalent Immobilization of Glucoamylase onto ρ-Benzoquinone-Activated Alginate Beads: II. Enzyme Immobilization and Characterization

A novel affinity covalent immobilization technique of glucoamylase enzyme onto ρ-benzoquinone-activated alginate beads was presented and compared with traditional entrapment one. Factors affecting the immobilization process such as enzyme concentration, alginate concentration, calcium chloride concentration, cross-linking time, and temperature were studied. No shift in the optimum temperature and pH of immobilized enzymes was observed. In addition, K _m values of free and entrapped glucoamylase were found to be almost identical, while the covalently immobilized enzyme shows the lowest affinity for substrate. In accordance, V _m value of covalently immobilized enzyme was found lowest among free and immobilized counter parts. On the other hand, the retained activity of covalently immobilized glucoamylase has been improved and was found higher than that of entrapped one. Finally, the industrial applicability of covalently immobilized glucoamylase has been investigated through monitoring both shelf and operational stability characters. The covalently immobilized enzyme kept its activity over 36 days of shelf storage and after 30 repeated use runs. Drying the catalytic beads greatly reduced its activity in the beginning but recovered its lost part during use. In general, the newly developed affinity covalent immobilization technique of glucoamylase onto ρ-benzoquinone-activated alginate carrier is simple yet effective and could be used for the immobilization of some other enzymes especially amylases.