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用葡萄糖酸对Fe3O4磁性纳米颗粒表面进行修饰,然后用水溶性碳化二亚胺(EDC)作偶联剂,对脂肪酶进行固定化。考察了偶联剂浓度、给酶量和反应时间对脂肪酶固定化过程的影响。结果表明,制备功能化磁性颗粒固定化酶的最佳条件为:偶联剂浓度为12.5mg/mL磷酸缓冲液(PBS),给酶量为2.5mg/mLPBS,反应时间为24h。固定化脂肪酶表现出优异的热稳定性,60℃时酶活为游离酶的6倍。重复使用10次后,酶促活力依然保持80%以上。 相似文献
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以凹土为原料,醋酸铁为γ-Fe2O3前驱体,湿法工艺制备了磁性凹土基复合材料,并用偶联剂γ-氨丙基三乙氧基硅烷对磁性凹土基复合材料进行了氨基改性。XRD、TEM、FT-IR、VSM表征结果表明:γ-Fe2O3粒子均匀负载于凹土层间,粒子直径为4~15 nm;经过改性,氨基接枝于磁性凹土基复合材料表面;改性前后的磁性凹土基复合材料均具超顺磁性,饱和磁强度分别为13.4和10.7 emu·g-1。以戊二醛为交联剂,以氨基化磁性凹土基复合材料为载体固定化假丝酵母脂肪酶,研究结果表明:相比于游离脂肪酶,固定化脂肪酶的热稳定性和p H稳定性显著提升,重复用于水解反应8次后仍保持约78%的活力,米氏常数是游离脂肪酶的1.28倍,且在外加磁场作用下易于从反应体系分离。 相似文献
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利用正硅酸甲酯(TMOS)和丙基三甲氧基硅烷(PTMS)为复合硅源,以PEG(MW=20000)为稳定剂,以HCl为催化剂,经过溶胶-凝胶过程包埋假丝酵母99-125脂肪酶. 研究得到最适的固定化条件为:PTMS与TMOS的摩尔比4: 1, R值(水与硅源的摩尔比)20, 给酶量(酶占硅源的质量百分数)3.71%, PEG与酶的质量比(1~1.5):1, 硅源水解时间35 min. 在该条件下,固定化脂肪酶的最高酯化活力是游离酶最高酯化活力的2.02倍. 固定化脂肪酶在100℃保温2 h后酶活仍维持为59.1%,固定化酶催化特定酯化反应,经过8批连续反应96 h后酶活维持不变. 相似文献
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开发了以磁性多孔微粒作为载体固定化脂肪酶的方法,进行了载体的FTIR、XRD、SEM、TEM、BET、TGA和VSM等测定与分析,考察了固定化时间、酶载量和缓冲液pH值等因素对固定化酶在有机相中催化烯丙醇酮转酯化反应性能的影响。结果表明,制备的磁性微粒是以Fe3O4为磁核,呈现多孔,比表面积12.16 m2 /g,平均孔径为171.7 nm,磁铁含量38%并为超顺磁性;在酶与载体质量比为1∶1、pH值8.0及固定化时间6 h制得固定化酶的效果最佳,固定化酶的活力回收率可达240%。以其作为载体制备获得固定化酶操作稳定性得到显著提高,重复利用30批次后残余活力为74.5%,而游离酶7批次后仅为37.1%。 相似文献
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利用接枝聚合在微米级硅胶微粒表面的甲基丙烯酸缩水甘油酯(GMA)和对羟基苯磺酸钠(SHBS)发生环氧基团的部分开环反应,制得阴离子型双功能复合载体SHBS-PGMA/SiO2,研究了辣根过氧化酶(HRP)与载体SHBS-PGMA/SiO2间的静电相互作用在共价固定HRP过程中的作用及其机理. 结果表明,在较大的pH值范围内,复合载体SHBS-PGMA/SiO2表面携带高密度负电荷,pH=6.0时HRP分子荷正电,酶蛋白分子与载体间会产生强静电相互作用,显著促进HRP的固定化;当载体表面SHBS的键合率约为18%时,静电相互作用对固酶的促进作用最强,固定化酶的偶联率和比活力最高. 离子强度对酶的固定化也有很大影响,加入NaCl对载体与酶蛋白之间的静电相互作用力产生屏蔽作用,增大NaCl浓度可使固定化酶的偶联率和比活力降低. 相似文献
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SBA-15-NH2 and SBA-15-Cl Mesoporous Materials were prepared by modifying SBA-15 with silane coupling agent 3-aminopropyltriethoxysilane and 3-chloropropyltriethoxysilane using the post-synthesis method. The mesoporous samples were characterized by Fourier transform infrared spectra and nitrogen adsorption. Compared with SBA-15-NH2, SBA-15-Cl has suitable pore opening for further utilization in the immobilization of Candida sp.99-125 lipase by physical adsorption. The influences of lipase concentration and immobilizing time on the immobilization efficiency were investigated. Meanwhile, the lipase immobilized on SBA-15-Cl showed higher thermal, pH and storage stability than that of free lipase. Further study demonstrated that lipase immobilized on SBA-15-Cl could be used eight times without significant decrease of enzyme activity. The phenomenon was associated with the shrinkage of the pore opening of SBA-15-Cl keeping lipase from leaping out. 相似文献
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引 言脂肪酶有机相酶催化在有机合成及手性药物合成中有重要用途[1],这些反应大都是在油水两相中进行 ,脂肪酶是一种界面酶 ,在两相界面上反应活性最高 .为增大比表面积 ,在反应体系中加入表面活性剂或采用反胶团体系进行脂肪酶催化反应[2 ],但加入表面活性剂后对后续产物的分离纯化带来不利影响 .采用酶膜反应器进行脂肪酶两相反应是近年来的一个发展方向 ,即将脂肪酶固定在膜上 ,油水两相分别走膜两侧 ,并在膜表面接触反应 ,反应生产的产物可及时被两相带走 ,从而避免了两相直接接触乳化的问题[3].目前脂肪酶是通过吸附或交联固定在疏水… 相似文献
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PREPARATION OF PVA/CHITOSAN LIPASE MEMBRANE AND ITS APPLICATION IN SYNTHESIS OF MONOGLYCERIDE 下载免费PDF全文
PVA/Chitosan(CS) composite membrane was used for enzyme processing of fats and oils. The concentration of lipase and cross-linking agent which influence the immobilization of lipase in membrane were determined. Epichlorohydrin is used as the cross-linking agent. The immobilized lipase is 0.66 u·cm -2 and the recovery of immobilized lipase is 24%. The membrane reactor was tested to synthesis monoglyceride(MG), which could be used many times without loss conversion yield of MG. The PVA/CS lipase membrane reactor is a new reactor for lipase catalytic biphase systems. 相似文献
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为研究天然黏土为载体固定化脂肪酶的可行性,采用羟基化、硅烷化处理,对黏土进行改性,并以此为载体吸附固定化脂肪酶,探讨黏土固定化脂肪酶的条件对酶活及蛋白吸附量的影响,优化固定化脂肪酶条件。研究结果表明:黏土经羟基化、硅烷化改性处理后能显著提高固定化酶活和蛋白固定量,其中硅烷化改性最优;载体固定脂肪酶最优条件为:加酶量50 mg/g,载体粒径180—250μm,pH值为4.0,固定化温度25℃,固定化时间2.0 h;与游离酶相比,固定化酶显示出更广的pH值适应性。黏土固定化脂肪酶重复使用10批次后,仍能保留76.85%的初始活力。以天然黏土为载体固定化脂肪酶,具有较好的实际可应用性及操作稳定性,在较低pH值条件下应用具有一定优势。 相似文献
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Lipase from Rhizopus niveus was immobilized by physical adsorption on Celite 545 and glass beads. The results showed that the highest immobilization
efficiency and specific hydrolytic activity of 96% and 9.2 meq/mg protein/min, respectively, were obtained with Celite as
the carrier. However, the specific hydrolytic activity of lipase adsorbed on glass beads by acetone precipitation was similar
to that obtained by the Celite carrier, although the protein loading capacity was relatively low. The results showed that
lipase immobilized on glass beads exhibited similar activity profiles with respect to reaction time, different enzyme concentrations,
and water content, using trimyristin and tripalmitin as substrates, to those obtained with the free enzyme. In contrast, the
immobilized lipase on Celite exhibited a considerably lower hydrolytic activity. However, the results also showed that the
lipase activities of the free enzyme and the immobilized Celite enzyme were similar when the more hydrophilic triolein was
used as the substrate. The interesterification of a mixture of tripalmitin and trimyristin or triolein was carried out using
both the free and immobilized enzymes. The results indicated that the hydrolytic activity of lipase was similar in both cases
for the first 24 h, after which it decreased dramatically. These findings suggest that at this late stage an equilibrium between
the hydrolytic and interesterification reactions was reached. 相似文献
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PREPARATION OF PVA/CHITOSAN LIPASE MEMBRANE REACTOR AND ITS APPLICATION TO SYNTHESIS OF MONOGLYCERIDE 下载免费PDF全文
PVA/ Chitosan (CS) composite membrane was studied in this paper, which could be used for enzyme processing of fat and oils. The parameters such as concentration of lipase, pH, and cross-linking agent as well as metal ions, which influence the immobilization of lipase in membrane, were optimized. The immobilized lipase was 0.66 u/cm2 and the recovery of immobilized lipase activity was 24%. The membrane reactor could be used to synthesize monoglyceride (MG) with many batches. 相似文献
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假丝酵母99-125脂肪酶促酯化合成生物柴油的研究 总被引:3,自引:0,他引:3
1 INTRODUCTION Biodiesel, that is long-chain fatty acid short-chain alcohol esters (methyl, ethyl, propyl and butyl ester), is produced by esterification of fatty acids or inter- esterification of oils and fats. These fatty acid alcohol esters are not only used as important industrial addi- tives and surfactants, but also used for biofuel. The biodiesel is a biodegradable, environmental friendly, renewable substitute of diesel fuel[1]. The traditional production of biodiesel is by chem- i… 相似文献