酪蛋白抗凝血口服液的制备及其活性的初步研究

以酪蛋白为原料,采用木瓜蛋白酶、菠萝蛋白酶、碱性蛋白酶和中性蛋白酶对酪蛋白进行混合酶水解,制备酪蛋白酶解液。采用正交试验优化4种酶酶解酪蛋白的生产工艺为:底物浓度为15%,四种酶浓度(g/mL)混合比例为1:1:1:2(V/V),水解温度为50℃,水解时间为4 h、pH为6.5。按照该工艺制备的酶解液抗凝血活性为40 ATU/mL。通过添加适量的防腐剂和矫味剂将酶解液制备成具有一定抗凝血活性和口感风味良好的口服液,进行了口服液的稳定性试验。     

水溶性多糖酶解过程分子量变化与动力学建模

以魔芋葡甘聚糖-β-甘露聚糖酶水解体系为例,研究了水溶性多糖酶解过程中产物的分子量变化与动力学行为.利用凝胶排阻色谱法和特性粘度法,分别测定了酶解物的分子量分布和重均分子量(-Mw),结果表明:随着反应的进行,酶解物分子量分布先变宽再逐渐变窄,这是由酶在底物反应体系中的镶嵌式分布,不均一的底物分子序列结构与酶分子的选择性剪切,酶剪切的多种途径以及酶与底物的结合模式等四种因素共同作用的结果;初始阶段酶解物(-Mw)先快速下降再逐渐趋于平缓,其速率与底物浓度有关;基于酶解产物重均分子量变化规律而建立的(1/-Mw)随反应时间t变化的动力学模型,确定了常见的水溶性多糖浓度下酶解过程为零级降解,并与实验结果相当一致.     

利用乳液酶膜反应器拆分萘普生甲酯实验研究

利用乳液酶膜反应器进行外消旋萘普生甲酯的水解反应,以制备光学纯对映体(S)-萘普生,反应同时从膜透过侧收集产物,实现反应分离一体化。实验研究了固定酶前后膜传质阻力和反应过程的水相跨膜通量,考察了透过侧的产物浓度、反应器的转化率、产量和对映体选择性。结果表明:固定化酶引起的传质阻力远大于膜本身的阻力;透过侧的产物浓度与水相渗透通量密切相关,通量较低时,产物浓度较高;固定化酶的初始反应速率为3.660μmol/(h.g),为自由酶的20倍以上,固定化酶的对映体过剩值为99%—100%,远高于自由酶的选择性,表明该反应体系为脂肪酶催化拆分反应提供了良好环境。     

超滤和反应器偶联组合进行干酪素酶解反应

在研究底物浓度对干酪素酶解反应影响的基础上 ,提出干酪素酶解反应应当以边分离边反应的形式进行。因此以三种不同的操作方法 (反应与膜分离分别进行 ;连续偶联反应 ;半连续反应和连续偶联反应组合 ) ,对超滤和反应器的偶联组合进行了研究。其中以半间歇与连续偶联反应器的偶联组合为最佳。当底物浓度为 10 0 g· L-1时 ,得率达到 97% ,比反应与分离分别进行的方式提高了 16 .7%。在此三种方法中 ,超滤对总氮的截留率分别为 σ1=0 .11+0 .0 81t;σ2 =0 .15 +0 .0 0 7t;σ3 =0 .2 1- 8.8× 10 -6t。反应与超滤同时进行时透过液的稳定膜通量为 3.5 L·h-1· m-2     

应用不同型式反应器对蔗渣酶水解的研究

采用预处理条件为：蔗煮时间5.5h,温度为155℃－160℃,压力为0.6MPa,pH为4．5的40目的纸浆蔗渣为底物,Yakult的Onozuka－R－10纤维酶为催化剂,在50℃,pH为4．8（醋酸－醋酸钠缓冲液）的条件下,考察了釜式和固定床反应器对酶解反应过程的影响,测定了在不同底物浓度,不同搅拌强度和不同循环流速对酶解反应还原糖得率影响。结果表明,对釜式反应器,底物浓度高,转化率低,搅拌强度加大对纤维素水解有利。对固定床反应器,循环流速增大,可提高蔗渣酶解的还原酶是率。对工业化过程来说,采用固定床反应器对蔗渣酶解反应比釜式反应器较为有利。     

竹黄两种预水解制备糠醛的工艺比较研究

为使竹屑资源得到充分利用,对两种预水解制备糠醛的工艺进行了比较探究。首先采用亚硫酸氢钠预处理和稀酸预处理对半纤维素进行提取,然后研究了反应温度、反应时间、硫酸浓度、戊糖初始浓度和NaCl用量对糠醛收率的影响,最后对水解底物的酶解效果进行了初步探究。在相同的酶解条件下,亚硫酸氢钠预水解底物酶解率高于稀酸水解底物酶解率。     

热动力学法研究间歇反应器中酶促反应动力学

用热动力学法研究了间歇反应器中单底物酶促反应动力学,并详细讨论了产物竞争性抑制作用对反应速率的影响.用微量热法研究了过氧化氢酶催化分解过氧化氢和精氨酸酶催化水解L-精氨酸的反应,实验验证了本文热动力学法研究间歇反应器中单底物酶促反应动力学的正确性.     

酶促反应色谱分离耦合过程参数分析

对酶促反应以谱分离耦合过程进行了反应动力学参数及操作参数分析,并以蔗糖酶促水解为模型反应进行了正交实验研究,结果表明,该耦合过程对产物非竞争性抑制的消除效果要优于竞争性抑制。产率对底物浓度最为敏感,其次为洗脱速率和进料体积,而转化率的敏感性次序由大到小依次为洗脱速率,底物浓度和进料体积。     

旋叶动态膜分离式酶解反应器酶解糊精的实验研究

研究了旋叶动态膜分离式酶解反应器的主轴转速、底物浓度和循环量等操作参数对糖化酶酶解糊精反应的影响 ,测定固定化酶反应的动力学参数 ,并对其适宜操作条件进行了探索     

动态膜分离式酶反应器连续操作特性研究

在应用动态膜分离技术开发研制的新型多功能酶解反应器上进行了边反应分离的连续操作过程。通过在该反应器上进行菊粉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研究。     

Performance of Perstractive Enzyme Reactor for Synthesis of Aspartame Precursor

A perstractive enzyme reactor was used for the synthesis of N-(benzyloxycarbonyl)-L -aspartyl-L -phenylalanine methyl ester (ZAPM), the precursor of the artificial sweetener, aspartame. The synthesis of ZAPM in the reactor proceeded by an enzymatic reaction between N-(benzyloxycarbonyl)-L -aspartic acid (ZA) and L -phenylalanine methyl ester (PM) in the aqueous phase. The synthesized ZAPM in the aqueous phase was mainly extracted into the organic phase, therefore, the concentration of ZAPM in the aqueous phase could be kept low. As a result, high conversion of ZAPM was obtained with this system. The partition coefficients of substances in the aqueous/butyl acetate biphasic system, the mass transfer coefficients of substances through the membrane and the enzymatic kinetics of ZAPM synthesis were determined experimentally. The reaction model which was based on the material mass balance equations was discussed to estimate the performance of the perstractive enzyme reactor system. The calculation values using the model and the experimental data showed good agreement with the concentration changes of the substances in the system. © 1997 SCI     

反应器操作方式对酶动力学拆分立体选择性的影响

描述了在批式反应器和连续流搅拌反应器（ＣＳＴＲ）中酶动力学拆分对映异构体的不同之处，从宏观反应器平衡角度，推导出了在ＣＳＴＲ反应器中不同于在批式反应器中的一定酶立体选择性（Ｅ）下，底物或产物的对映体过量值与反应的转化率之间关系的定量关系式。并通过商品脂肪酶及芽胞杆菌Ｅ－５３脂肪酶催化的萘普生甲酯的不对称水解反应得到了证实。分别在批式反应器和ＣＳＴＲ反应器中进行萘普生的酶法拆分，在一定转化率下，批式     

Analysis of process integration and intensification of enzymatic cellulose hydrolysis in a membrane bioreactor

Enzymatic cellulose hydrolysis has been studied for many years, generating rich literatures and knowledge in respect to the underlying reaction mechanism, reaction kinetics, and bioreactor systems. This paper attempts to offer some additional information and new understanding of how reaction kinetics and reactor productivity can be improved in a process involving simultaneous reaction and product separation using a purpose‐built membrane reactor with a single combined reaction zone and separation zone. Different operating strategies of batch, fed batch and continuous cellulose hydrolysis were investigated with intermittent or simultaneous removal of products (reducing sugars) to reduce enzyme inhibition and improve reactor productivity. The effect of continuous and selective product removal, reduced enzyme inhibition and higher enzyme concentration in retention were examined for the potential benefit in process integration and intensification in order to lower the high process cost of the enzymatic hydrolysis process, mainly due to slow reaction kinetics and expensive enzymes. A mathematical model was offered to account for the effect of selective product (reducing sugars) separation, permeate flux, reduced cellulase inhibition, dynamic structural change of the solid substrate and possible shear deactivation of the enzyme. Computer analysis was also carried out to analyse the quasi‐steady state of the reaction intermediates in order to gain an insight into the reaction mechanism in simultaneous reaction and separation systems. Some original analysis and simulation of the effect of membrane separation parameters on the overall reactor performance is offered, including the effect of membrane selectivity (rejection coefficient) and flux. Copyright © 2005 Society of Chemical Industry     

Enzymatic Hydrolysis of Cassava Starch into Maltose Syrup in a Continuous Membrane Reactor

This study deals with the use of a membrane reactor for the enzymatic conversion of cassava starch to maltose. The enzymes used were Maltogenase and Promozyme (Novo Nordisk). Maltogenase activity was unaffected after a 5 h incubation period at 65°C, but Promozyme was markedly heat-unstable even at 37°C. Batch hydrolysis of liquefied cassava starch (30% w/w) by Maltogenase and Promozyme resulted in a maximum degree of starch conversion to maltose of 72% (≈254 g dm⁻³ maltose). The conversion degree fell by 11% when no debranching enzyme was used. The residence time distribution of the ultrafiltration reactor (UFR) was that of an ideal continuously stirred tank reactor. Rejection of Maltogenase by Carbosep M4 membranes (MWCO: 50 kDa) was not total. The overall enzyme activity loss after a 5 h diafiltration period was 28%, however about half this loss appeared to be due to enzyme denaturation inside the reactor. During saccharification trials conducted in the UFR at a starch concentration of 30% (w/w), severe membrane fouling occurred. The average permeate fluxes obtained were 14 and 23 dm³ h⁻¹ m⁻² at constant transmembrane pressures of 100 and 200 kPa respectively. When the reactor was operated at a space-time of 4·2 h, the degree of starch conversion to maltose in the permeate rapidly stabilized around 55–56%. © 1997 SCI.     

Enzymatic production of fructooligosaccharides from inexpensive and abundant substrates using a membrane reactor system

The concept of zero waste in the sugar industry has encouraged the development of technologies that promote utilization of by-products, including the enzymatic conversion of waste feed stocks into nutraceutical products. Here we investigated a membrane reactor for the production of fructooligosaccharides (FOS) with immobilized enzyme (Pectinex Ultra SP-L) system using pretreated molasses as substrate with cleaning efficiency and less fouling as performance tools. The resulting spectra showed a high FOS yield of 63% with 89% conversion from available sucrose. So, the enzymatic membrane reactor system with innovative continuous separation of enzyme was proved to fit for the production of FOS.     

A Novel Exponential Kinetic Model for Casein Tryptic Hydrolysis to Prepare Active Peptides

The kinetics of casein tryptic hydrolysis to prepare active peptides was investigated. Taking into account the reaction mechanism including single substrate hydrolysis, irreversible enzyme inactivation, and substrate inhibition, a set of exponential equations was established to characterize the enzymatic hydrolysis curves. The verification was carried out by a series of experimental results and indicated that the average regressive error was less than 5%. According to the proposed kinetic model, the kinetic constants and thermodynamic constants of the reaction system were also calculated.     

纸浆蔗渣酶法水解反应过程的考察

以蒸煮时间5．5小时,温度为155－160℃,P=0.6MPa,pH为4．5的40目的纸浆渣为底物,日本Yakult生物化学试剂公司的Onozuka-R-10纤维素酶为催化剂,在50℃,PH为4．8（乙酸－乙酸钠缓冲液）的条件下,考察了釜式和固定床反应器对酶解反应过程的影响,测定了在不同底物浓度时的酶解反应还原糖得率,探讨了酶的吸附以及酶活性在酶解反应过程的变化情况。实验结果表明,在本实验条件下,底物浓度高,转化率则低,固定床反应器对酶的吸附比釜式反应器略多;酶的活性变化在两种反应器中几乎没多大差别。     

玉米秸秆半纤维素制备木糖醇的研究

首先采用无污染的碱性过氧化氢法研究了半纤维素的分离与提取,然后对提取的半纤维素分别进行化学水解和酶水解比较,最后研究了水解液发酵制备木糖醇。结果表明,半纤维素分离提取的优化参数为:2%过氧化氢,2%氢氧化钠,加热时间4 h,反应温度75℃。使用CF3COOH水解半纤维素所得木糖含量为67%~73%,水解率为76%~84%,稀盐酸预处理半纤维素再化学水解所得木糖含量高达88%,水解率上升至大约90%。半纤维素的酶水解实验表明,木聚糖酶的水解专一性高于半纤维素酶,木聚糖酶水解率为38%~60%。在水解液发酵实验中,酶水解液的木糖醇转化率高于化学水解液。另外,通过浓缩半纤维素水解液,提高发酵液的木糖初始浓度,有利于菌株生长,可以提高木糖醇转化率。研究对于玉米秸秆半纤维素制备化学品具有一定的指导意义。     

Potential of Integrated Semi-Continuous Enzymatic Synthesis and Filtration Processes for Efficiency Enhancement

Galacto-oligosaccharides (GOS), increasingly popular prebiotics, are synthesized by enzymatic conversion of lactose. Among others, the total production costs are significantly influenced by the costly enzyme. Therefore, it was investigated if the reuse and full recovery of the enzyme is feasible, followed by the development of a semi-continuous process in order to maintain a consistent high GOS yield. As a preliminary step, the enzyme-catalyzed reaction was recorded within the permissible operating parameters. It was successfully shown that steady high GOS yields can be synthesized semi-continuously within a filtration plant functioning as an enzymatic membrane reactor.     

玉米秸秆酶水解条件的优化研究

采用响应曲面法对玉米秸秆酶水解反应进行了评价,从而确定玉米秸秆酶水解反应的优化条件为底物中酶浓度57.5 FPU/g,底物质量浓度64.7 g/L,温度48℃,pH值4.8,反应时间49 h。在此条件下,每100 g底物还原糖产量为46.34 g,与模型预测值46.43 g底物非常接近。与单因子实验相比,酶浓度降低了2.5 FPU/g,底物质量浓度提高了14.7 g/L,反应时间缩短了23 h,还原糖产量提高10.41%。响应曲面法优化玉米秸秆酶水解是合理有效的,得到的优化条件有利于玉米秸秆的转化生产还原糖。