有机相中壳聚糖-海藻酸固定化脂酶的特性

研究了壳聚糖 海藻酸固定化脂酶在有机相反应中的稳定性与活性。考察了凝胶时间、壳聚糖浓度及壳聚糖分子质量对固定化脂酶包埋率与活性的影响 ,确定了适宜 pH值与批反应时间。同时讨论了溶剂极性和操作时间对固定化酶稳定性的影响。测定了固定化脂酶水解橄榄油反应的动力学参数。结果表明 ,壳聚糖 海藻酸聚电解质膜可提高固定化酶的包埋率与稳定性     

以壳聚糖为载体固定化青霉素酰化酶的研究

介绍了以壳聚糖为载体固定化青霉素酰化酶需首先制备壳聚糖颗粒 ,使用戊二醛、甲醛、乙二醛 3种活化剂处理所得的壳聚糖颗粒 ,确定了以戊二醛为活化剂交联其上的氨基共价结合青霉素酰化酶的固定化方法。从戊二醛的浓度、pH值、固定化时间、固定化pH值、酶用量等条件摸索了最佳固定化条件 ,获得了酶活力为4 0 0 0 0U/ (g·h)、回收率为 5 0 %左右的固定化青霉素酰化酶。     

磁性壳聚糖微球的制备及其固定化乳糖酶的研究

采用水热法制备得到磁性Fe_3O_4纳米粒子,以壳聚糖、制备的Fe_3O_4为原料,采用乳化交联法成功制备了磁性壳聚糖微球,并通过SEM、FTIR、VSM、XRD对其进行表征。进一步以制备的磁性壳聚糖微球为载体,采用吸附法制备磁性壳聚糖微球固定化乳糖酶。以酶活力为考察指标,研究了不同固定化条件对制备固定化酶的影响,以及固定化酶的酶学性质。结果表明,乳糖酶的最佳固定化条件为:固定化时间4 h,pH为7.0,乳糖酶酶液浓度为0.6 mg/mL,固定化酶相对于游离酶的pH稳定性和温度稳定性均有一定程度的提高,固定化酶重复使用5次后,酶活仍保留65%以上。     

壳聚糖及其衍生物作为固定化蛋白酶的载体

介绍了以壳聚糖及其衍生物为载体的木瓜蛋白酶、微生物蛋白酶和胰蛋白酶的固定化条件和固定化方法;强调了酶活力回收率、稳定性的重要性;指出了壳聚糖及其衍生物作为固定化蛋白酶的载体具有环保、来源丰富和可以通过多种方法进行固定化处理的优点。     

假丝酵母产脂肪酶在壳聚糖和硅胶上的固定化研究

本实验分别壳聚糖和氨基化后的硅胶作为固定化载体,用戊二醛作为交联剂,将脂舫酶共价固定化于载体上,壳聚糖的最佳固定化条件是戊二醛浓度2．5％,给酶量为4125U／g,氨基化硅胶的最佳固定化条件为戊二醛浓度2％,最佳给酶量在3456U／g,固定化酶活为2952U／g,最佳酶活表现率为85％。两种方法所得的固定化酶的耐温性和储藏稳定性都有了显著提高。氨基化硅胶固定化酶在50℃下保温3小时后仍保留有14％的酶活。结果显示假丝酵母产脂肪酶固定于弱亲水性载体上要比固定于强亲水性载体上效果更好。     

载脂肪酶壳聚糖/海藻酸钙微胶囊的制备

针对固定化脂肪酶的研究背景,以壳聚糖、海藻酸钠为微载体制备材料,采用脉冲电场液滴工艺制备壳聚糖/海藻酸钙微胶囊。以脂肪酶为生物模型,系统考察了制备条件对载脂肪酶壳聚糖/海藻酸钙微胶囊酶活力的影响。结果表明:海藻酸钠质量浓度和酶与海藻酸钠载体配比是影响固定化酶活力的主要因素,载酶量为15mg/mL,海藻酸钠质量浓度为10mg/mL时载酶微胶囊酶活力最高,球形度好。通过改变壳聚糖质量浓度和相对分子质量,可以调控微胶囊膜的厚密程度进而影响固定化酶活力。成膜液pH值依次影响壳聚糖与海藻酸盐分子中官能团的电离状态、成膜反应静电络合程度、酶蛋白包封率,最终影响固定化酶活力。在载酶量为15mg/mL,海藻酸钠质量浓度为10mg/mL,壳聚糖相对分子质量、质量浓度和pH值依次为50kDa、1mg/mL和3.0的条件下,固定化酶活力为187IU/g。     

磁性壳聚糖微球固定化酵母细胞及其用于发酵生产酒精的研究

通过溶胀一吸附法用磁性壳聚糖微球固定化酵母细胞,考察了磁性壳聚糖微球固定化酵母细胞的效果.结果表明,大量酵母细胞被固定在磁性微球表面,且磁性壳聚糖微球可重复使用.以所制备的磁性固定化酵母细胞发酵生产酒精,发酵醪液的酒精度高于悬浮酵母细胞发酵醪液的酒精度,重复使用磁性壳聚糖微球固定化酵母细胞再次发酵,醪液的酒精度虽然有所下降,但是仍高于悬浮酵母细胞发酵的酒精度.     

壳聚糖载体柔性固定化木瓜蛋白酶

用酶柔性固定化模型,以壳聚糖为载体,双醛淀粉为柔性链,对木瓜蛋白酶进行柔性固定化. 通过对固定化条件的优化,得出选用壳聚糖、双醛淀粉制得的柔性载体(Chitosan-DAS50)在酶用量为14.4 mg/g(酶/干球)、pH 8的条件下,固定木瓜蛋白酶18 h,所得的固定化酶活力回收率达72%,相当于采用壳聚糖-戊二醛(Chitosan-GA)手臂载体的3倍. 结果表明,酶的柔性固定化模型可以改善传统共价结合法固定化及手臂固定化酶活力回收率不高的缺陷.     

AS1.398中性蛋白酶的固定化研究

利用壳聚糖为载体，戊二醛为交联剂，对AS1．398中性蛋白酶进行了固定化研究，固定化反应的最佳条件是采用1％的戊二醛浓度，壳聚糖和戊二醛的交联反应时间为4h，加入酶固定化反应12h，固定化酶的最适温度35℃，最适pH值8．0。得到的固定化酶的活力回收平均为82．5％，固定化酶的稳定性能好于游离酶。     

磁性壳聚糖微球的合成及其在固定化血管紧张素转化酶的应用

以化学共沉淀法合成Fe3O4纳米粒子为磁核,采用乳化交联法制备磁性壳聚糖微球,并对其形貌、结构和磁饱和强度等性质进行了表征。以磁性壳聚糖微球作为载体,固定化猪肺粗提物中的血管紧张素转化酶,并对固定化条件进行研究。结果表明,固定化血管紧张素转化酶的最佳条件为：pH值为8.3,最佳温度为50 ℃,最佳时间为1.5 h,最佳酶溶液蛋白浓度为6 mg/mL,此时固定化酶活力最高为0.048 U/g微球。与游离酶相比,固定化酶的pH值稳定性和热稳定性均得到提高。固定化酶重复使用10次,仍然保持40%以上相对活力,说明磁性壳聚糖微球是固定化血管紧张素转化酶的良好载体。     

微球型壳聚糖胺基吸附剂的制备及性能

以壳聚糖为原料,采用反相悬浮交联的方法制取微球型壳聚糖颗粒,再进行羟丙基氯化及胺基化,制备了一系列新型壳聚糖胺基衍生物微球。衍生物的胺基含量明显提高,碱性增强。并初步考察其吸附牛血清白蛋白（ＢＳＡ）性能。可用作新固定化酶载体及生化分离材料。     

固定化细胞载体材料的研究进展

固定化细胞技术是在固定化酶的基础上发展起来的高新技术,所用载体材料的性能是此项技术的关键。详细介绍了固定化细胞技术中常用载体材料的种类及其性能,概述了新近出现的载体材料及其应用,最后对载体材料的未来发展进行了预测。     

Study on the activity and stability of urease immobilized onto nanoporous alumina membranes

Nanoporous alumina membranes were employed as substrate materials for urease immobilization. Anodic porous alumina was prepared by the two-step anodization of high purity aluminum. By controlling anodization conditions, the nanoporous structure with desired dimension was obtained. Urease immobilization onto nanoporous alumina membranes was performed by four different protocols. Effect of pore diameter, pore length and immobilization methods on the activity and stability of immobilized enzyme was discussed in detail. The results show that the enzymes immobilized onto porous alumina with big pore diameter possess high activity and poor stability as compared to small pore diameter. The effect of pore length is complicated, the activity of enzyme increases with the increasing pore length for big pore size; while for correspondingly small pore size, enzymatic activity slightly depends on pore length. The immobilization methods have a slight effect on enzymatic activity, whereas enzyme immobilization by chitosan coating and reticulation with glutaraldehyde exhibits a good long-term stability as compared to that only via physical adsorption.     

Loofa immobilized Bacillus sp. DSM 2523 as a whole cell biocatalyst for production of cyclodextrin glucanotransferase in an airlift reactor with a net draft tube

Cyclodextrin glucanotransferase (CGTase) production was studied using loofa-immobilized Bacillus sp. DSM 2523 and starch substrate. The bacterial cells from 2- and 4-day old cultures were used in the flask studies. Loofa and chitosan were added for cell immobilization and cell flocculation, respectively, and different treatments were considered according to the timing of their addition. The cell responses were evaluated for their degree of cell immobilization and level of CGTase activity. With the use of the selected treatment, testing was carried out in an airlift reactor with a net draft tube having specific geometric properties. The cell capacity for reusability also was examined. The production of CGTase was higher in the second cycle in the reactor operated at 0.25 vvm where the enzyme activity reaching 0.20?U/ml within 2?h. In the flask experiments, CGTase activity reached 0.23?U/ml after 19?h in the second cycle.     

氨基功能载体固定化酶研究进展

综述了甲壳素、壳聚糖天然氨基功能载体和氨基化硅胶化学合成载体的制备方法,并介绍了利用戊二醛直接固定、载体活化和酶活化固定化酶的方法,最后对氨基功能载体固定化酶的发展趋势加以评述:在利用氨基功能载体固定化酶过程中,有必要有针对性地合成一些新的氨基功能载体,使其反应条件更温和、酶的固载量更大、酶活力回收率更高、稳定性更强。或者针对特定的载体和酶,通过结合配体、添加稳定剂、固定前修饰、固定后修饰和后固定化技术处理等方法,进一步改善固定化酶的性能。     

用固定化L-赖氨酸脱羧酶细胞制备1,5-戊二胺

研究了4种固定化蜂房哈夫尼菌(H.alveiAS1.1009)菌体细胞的材料和方法,包括海藻酸钙包埋法、半透膜透析袋法、海藻酸钙-明胶交联包埋法和明胶包埋法。其中海藻酸钙包埋法稳定性最好,该方法最优转化条件为:在ρ(海藻酸钠)=30g/L的水溶液中,最适菌体质量浓度为ρ(菌体)=30.8g/L,100mL转化液中海藻酸钙球体体积为30mL,转化最适温度为37℃,最适pH=5.0。用该方法转化测得比酶活可达1028.9U。重复性佳:第一批固定化细胞酶活可达游离菌体的98.62%,第四批可达第一批酶活的38.68%。     

酶固定化无机载体材料的研究进展

近年来,酶固定化技术已在食品工业、医药、精细化学品工业,尤其是手性化合物等行业得到广泛应用,在废水处理方面也取得了一定进展。然而,载体材料的物理和化学性能直接影响固定化酶的催化活性。本文介绍了酶固定化常用无机载体材料一传统的无机载体材料、改性无机载体材料以及复合载体材料,并对酶固定化用无机载体材料的发展进行了展望。     

无机材料在酶固定化中的应用

综述了近年来无机材料在国内外酶固定化研究中的应用,着重介绍了载体材料的表面处理方法及相应的酶固定化方法,并对无机材料在酶固定化中的应用作了展望。     

Immobilization of chitosan on nylon 6,6 and pet granules through hydrolysis pretreatment

Chitosan has been increasingly studied as an adsorbent for removing heavy metal ions and organic compounds from aqueous solutions. Most of the studies used chitosan in the form of flakes, powder, or hydrogel beads. This research investigates the immobilization of chitosan on other granular materials to overcome the poor mechanical property of chitosan and offers the potential for chitosan to be used as a regenerable adsorbent. Nylon 6,6 and poly(ethylene terephthalate) (PET) granules were partially hydrolyzed under an acidic or alkaline condition to allow chitosan to be coated or immobilized on the granules' surfaces. The surface morphologies of nylon 6,6 or PET granules before and after hydrolysis and those with immobilized chitosan layer were examined by scanning electron microscopy (SEM), and their surface properties were characterized through ζ‐potential analysis and X‐ray photoelectron spectroscopy. The immobilization of chitosan on nylon 6,6 or PET granules was identified to be through the formation of the salt structure (–NH…^?OOC–) between the surfaces of hydrolyzed nylon 6,6 or PET granules and the chitosan layer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3973–3979, 2003     

Immobilization of a nonspecific chitosan hydrolytic enzyme for application in preparation of water‐soluble low‐molecular‐weight chitosan

A nonspecific chitosan hydrolytic enzyme, cellulase, was immobilized onto magnetic chitosan microspheres, which was prepared in a well spherical shape by the suspension crosslinking technique. The morphology characterization of the microspheres was carried out with scanning electron microscope and the homogeneity of the magnetic materials (Fe₃O₄) in the microspheres was determined from optical micrograph. Factors affecting the immobilization, and the properties and stabilities of the immobilized enzyme were studied. The optimum concentration of the crosslinker and cellulase solution for the immobilization was 4% (v/v) and 6 mg/mL, respectively. The immobilized enzyme had a broader pH range of high activity and the loss of the activity of immobilized cellulase was lower than that of the free cellulase at high temperatures. This immobilized cellulase has higher apparent Michaelis–Menten constant K_m (1.28 mg/mL) than that of free cellulase (0.78 mg/mL), and the maximum apparent initial catalytic rate V_max of immobilized cellulase (0.39 mg mL^?1 h^?1) was lower than free enzyme (0.48 mg mL^?1 h^?1). Storage stability was enhanced after immobilization. The residual activity of the immobilized enzyme was 78% of original after 10 batch hydrolytic cycles, and the morphology of carrier was not changed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1334–1339, 2006