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1.
将生物材料通过静电纺丝制备成的纳米纤维,具有比表面积大、空隙率高、生物相容性好等优点,因此得到广泛研究。本文主要综述了近年来国内外静电纺丝制备丝素蛋白纳米纤维的研究现状,重点介绍了采用不同溶剂制备的纯丝素蛋白纳米纤维和丝素蛋白与其它材料复合制备的丝素蛋白复合纳米纤维,并展望丝素蛋白纳米纤维潜在的应用前景。  相似文献   

2.
丝素蛋白膜上5-氟尿嘧啶的包埋及其释放   总被引:12,自引:0,他引:12  
讨论了包埋在丝素膜中的5-氟脲嘧啶(5-FU)的固定状况,在不同PH值下测定了丝素5-FU复合膜中药物的释放,实验结果表明:5-FU均匀地被包埋在丝素膜中,即丝素膜可以作为5-FU载体,经过比涂层保护,丝素5-FU复合膜中的5-FU溶解释放速率变慢,释放时间延长;经涂层的 素5-FU复合膜在接近丝素蛋白等电点(PH=4.5)时,5-FU在溶液中释放速度较慢,释放时间较长,表明用调节外部溶液PH值的  相似文献   

3.
众多的研究已表明生物材料的表面润湿性(wettability)对于细胞的粘附有重要的影响.在通过浇铸成膜并辅以乙醇后处理方法制备非水溶性再生丝素蛋白膜的基础上,我们采用紫外光辐照的方法以改变此类丝素蛋白膜的表面特性.接触角测试的结果显示,随着紫外光照时间的增加,丝素蛋白膜表面与水的接触角逐渐降低,最终可以达到超亲水的状态;表面X射线光电子能谱(XPS)分析表明,这是由于丝素蛋白膜表面亲水性基团(包括羧基和羰基等)的含量随着紫外光照时间的延长而增加所致.同时我们发现,经紫外光辐照一定时间后,再生丝素蛋白膜的力学性能并没有发生显著的降低.显然,此类具有较高力学性能且表面亲水性能较好的再生丝素蛋白膜有可能被进一步应用于生物医学领域.  相似文献   

4.
采用不同油相制备了系列丝素蛋白乳液,研究了丝素蛋白浓度、油相体积分数和油相极性对丝素蛋白的乳化活性指数、丝素蛋白乳液的稳定性和类型及乳液液滴的微观形态、粒径与zeta电位的影响,探讨了丝素蛋白的乳化活性和乳液稳定机制.结果表明,丝素蛋白具有两亲性和表面活性,可在油水界面富集并形成稳定的黏弹性保护膜;丝素蛋白的乳化活性随其浓度的增大而减小,随油相体积分数的增大而增大;丝素蛋白浓度和油相体积分数的增加可提高稳定乳液体积分数.  相似文献   

5.
含巯基/二硫键聚合物生物材料具有多种良好的性能,作为药物、基因等的释放载体在生物医学领域具有广泛的应用前景。随着基因工程和组织工程的发展,含巯基/二硫键聚合物生物材料的可生物降解性得到高度重视,而怎样改善其降解性能成为限制其应用的关键因素。由于二硫键在细胞外环境里保持稳定,在细胞溶质的还原环境中容易发生断裂,因此在制备新型基因、药物等释放载体上,二硫键充当了重要的角色,它的引入为聚合物生物材料的生物降解性能的设计与改善提供了一条重要的途径。本综述重点以聚合物水凝胶、聚合物微胶束、囊泡等为例,从巯基/烯的光聚合反应、Michael加成反应、氧化还原反应的角度,介绍了巯基/烯在聚合物中形成二硫键的不同途径的研究进展,并详细论述了基因载体、蛋白质载体、小分子药物载体三种还原敏感型材料的制备、表面修饰和改性的进展情况,进一步强调含巯基/二硫键聚合物生物材料的研究在生物医学领域应用的重要性。  相似文献   

6.
生物材料聚酰胺-胺树状大分子在医学领域研究进展   总被引:9,自引:0,他引:9  
聚酰胺-胺(PAMAM)树状大分子是一类新型纳米生物材料,这类分子可通过有机合成的方法精确控制分子的结构和相对分子质量,其独特的分子结构使之在许多领域获得广泛应用,本文着重介绍了PAMAM树状大分子作为基因载体,药物载体,磁共振造影剂和硼中子俘获治疗试剂等在医学领域中的研究进展。  相似文献   

7.
丝素纳米颗粒的制备及应用于L-天冬酰胺酶的固定化   总被引:2,自引:0,他引:2  
丝素蛋白纤维溶于高浓度中性盐溴化锂溶液或氯化钙-乙醇-水三元溶剂中, 经过透析和纯化可以制成3种液态丝素. SDS-PAGE分析结果表明, 其分子量分布范围明显不同. 应用能与水混溶的有机溶剂如丙酮等可将这种丝素制成丝素纳米颗粒, 用SEM观察到丝素纳米颗粒粒径分布范围为50~120 nm. 以戊二醛为交联剂, 将治疗急性淋巴性白血病常用酶制剂L-天冬酰胺酶共价结合在丝素纳米颗粒上. 酶活性分析结果表明, 由肽链断裂较少的丝素制备的纳米颗粒更适合于酶的生物结合. 酶动力学研究结果表明, 这种固定化酶活性回收率为44%, 热稳定性较游离酶有明显提高, 最适pH值范围加宽为6.0~8.0, 最适反应温度提高10 ℃; 抗胰蛋白酶水解能力明显增强. 结果表明, 丝素纳米颗粒与丝素蛋白膜一样, 是一种酶固定化的良好载体, 在药物缓释系统方面具有潜在的研究和开发价值.  相似文献   

8.
杨宇红  邵正中  陈新 《化学学报》2006,64(16):1730-1736
通过一系列光谱实验手段研究了再生桑蚕(Bombyx mori)丝素蛋白在水溶液中的构象转变情况. 由于丝素蛋白含有较多带电荷的氨基酸残基, 因此环境pH值对丝素蛋白的结构有着一定的影响: 酸性越强, 丝素蛋白越容易发生从无规线团到β-折叠结构转变; 相对而言, 碱性条件则更有利于丝素蛋白以无规线团结构稳定存在. 特别是当pH在4附近时, 丝素蛋白的无规结构最易发生改变; 而pH为6左右时, 丝素蛋白的结构则较为稳定. 这种变化趋势与沿着成熟蚕腺体中丝素蛋白所处的环境及其状态相当吻合, 由此表明pH值的调节是蚕在生物体中控制其丝素蛋白状态的一个相当重要的手段. 这一结果对人工纺制动物丝条件的调控有着极其重要的现实意义. 同时我们还发现, 在相当宽的pH范围内, 丝素蛋白的二级结构存在着中间体形态, 表明丝素蛋白的变性过程不符合简单的二态机制.  相似文献   

9.
骨形态发生蛋白-2(BMP-2)的缓释载体一直是骨组织工程中的研究热点.本研究通过化学改性制备了两种肝素化丝素支架,并浸渍吸附BMP-2,研究了BMP-2在不同丝素支架样品上的吸附能力、体外释放性能及其对人骨肉瘤细胞MG-63碱性磷酸酶活性(ALP)的影响.结果表明,肝素化丝素支架对BMP-2具有较强的吸附能力,并能保持其体外缓慢释放性能;MG-63细胞在肝素化支架上生长状态良好,并具有显著的增殖能力,负载BMP-2后的肝素化支架能显著促进MG-63细胞的分化.因此,肝素化丝素支架是一种较理想的BMP-2缓释载体.  相似文献   

10.
采用溶液浇注法制备丝素蛋白薄膜,应用傅里叶红外光谱(FTIR)和X射线衍射(XRD)研究了浓度不同的甲醇-水混合溶剂处理后丝素蛋白薄膜的结构变化,并以罗丹明B为模型药物与丝素蛋白构建药物缓释体系,考察了丝素蛋白膜的结晶结构对药物释放动力学的影响.结果显示,在甲醇体积比浓度MeOH=50%~90%的范围内,丝素蛋白材料中以β-折叠为主的silk II结晶含量随着混合溶剂中甲醇浓度的增加而先增加后下降,在MeOH=80%附近出现最大值.罗丹明B从丝素蛋白膜的释放属于Fickian扩散机理,其扩散指数n随着丝素蛋白膜中β-折叠含量的增加而增加,silk II结晶是丝素蛋白材料药物释放的天然调节器.  相似文献   

11.
Rational design of enzymes is a stringent test of our understanding of protein structure and function relationship, which also has numerous potential applications. We present a novel method for enzyme design that can find good candidate protein scaffolds in a protein-ligand database based on vector matching of key residues. Residues in the vicinity of the active site were also compared according to a similarity score between the scaffold protein and the target enzyme. Suitable scaffold proteins were selected, and the side chains of residues around the active sites were rebuilt using a previously developed side-chain packing program. Triose phosphate isomerase (TIM) was used as a validation test for enzyme design. Selected scaffold proteins were found to accommodate the enzyme active sites and successfully form a good transition state complex. This method overcomes the limitations of the current enzyme design methods that use limited number of protein scaffold and based on the position of ligands. As there are a large number of protein scaffolds available in the Protein Data Band, this method should be widely applicable for various types of enzyme design.  相似文献   

12.
Adsorption and proteolytic activity of the enzyme subtilisin Carlsberg have been studied on an immobilized, multilayer ovalbumin film. The cross-linked multilayer substrate permits protease adsorption to be examined unencumbered by the surface inhomogeneity typically observed in monolayer studies of protease surface kinetics. Decline of the protein film was measured over time using ellipsometry. Resulting kinetic data as a function of aqueous enzyme concentration and temperature were well fit by a Langmuir-Michaelis-Menten model for surface proteolysis. We observed that both the protein degradation kinetics and the in situ adsorption data were well described by the proposed model. The temperature dependence of the kinetic rate parameter yielded an activation energy of 12 kcal/mol. Further, the apparent Langmuir adsorption equilibrium constant of the enzyme at the protein/aqueous interface was 0.11 L/mg at 22 degrees C, 0.034 L/mg at 36 degrees C, and 0.011 L/mg at 50 degrees C. Although enzyme adsorption at a given aqueous enzyme concentration decreased at higher temperature, the enzyme cleaved the substrate more rapidly, leading to a net increase in the ovalbumin film degradation rate. We observed that the maximum enzyme coverage on the immobilized protein surface was approximately 40% of a close-packed monolayer at ambient temperature (22 degrees C).  相似文献   

13.
利用毛细管作为酶固定化的载体,将酶直接键合到毛细管内壁,制成毛细管纳升反应器,结合质谱分析水解产物,获得了蛋白质的肽谱,实验发现,以毛细管为反应器后,蛋白质肽谱分析所需量大大减少,只需 10^-13mol,甚至几个10^-15mol的量就可满足分析要求。  相似文献   

14.
15.
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.  相似文献   

16.
杨缜 《化学进展》2005,17(5):0-930
酶在有机溶剂中催化作用的研究日益受到重视,其应用范围也越来越广.本文就有机介质中酶催化的基本原理进行了讨论,包括酶的结构和催化机理,以及溶剂和水对酶的结构和催化功能的影响.同时,本文归纳出提高酶活性的一系列方法,其中不少方法简便易行,能使酶活性提高102-105倍.  相似文献   

17.
Compared to other typical cleaning agents, application of enzyme in cleaning of membranes fouled with protein solution promised the high cleaning efficiencies with lower environmental impact. This paper is focused on the mechanisms of protein removal by enzyme cleaning agent from the membrane surface by analysis hydraulic resistance, total protein removal using Lowry method, and membrane surface analysis using MALDI-MS and gel electrophoresis to estimate the foulant composition. Using single and binary protein solutions of bovine serum albumin and beta-lactoglobulin as the feed solution for filtration process, the experimental results indicate that optimum cleaning time and cleaning agent concentration is due to the competition between foulant removal and deposition of enzymes on the membrane during the cleaning process. The removal rate of different protein species in the fouling layer is varied, indicating that cleaning strategies can be tailor-made for fouling layer with different protein compositions.  相似文献   

18.
The origin of substrate preference in promiscuous enzymes was investigated by enzyme isotope labelling of the alcohol dehydrogenase from Geobacillus stearothermophilus (BsADH). At physiological temperature, protein dynamic coupling to the reaction coordinate was insignificant. However, the extent of dynamic coupling was highly substrate‐dependent at lower temperatures. For benzyl alcohol, an enzyme isotope effect larger than unity was observed, whereas the enzyme isotope effect was close to unity for isopropanol. Frequency motion analysis on the transition states revealed that residues surrounding the active site undergo substantial displacement during catalysis for sterically bulky alcohols. BsADH prefers smaller substrates, which cause less protein friction along the reaction coordinate and reduced frequencies of dynamic recrossing. This hypothesis allows a prediction of the trend of enzyme isotope effects for a wide variety of substrates.  相似文献   

19.
Through characterization of the solvent isotope effect on protein dynamics, we have examined determinants of the rate limitation to enzyme catalysis. A global conformational change in Ribonuclease A limits the overall rate of catalytic turnover. Here we show that this motion is sensitive to solvent deuterium content; the isotope effect is 2.2, a value equivalent to the isotope effect on the catalytic rate constant. We further demonstrate that the protein motion possesses a linear proton inventory plot, indicating that a single proton is transferred in the transition state. These results provide compelling evidence for close coupling between enzyme dynamics and function and demonstrate that characterization of the transition state for protein motion in atomic detail is experimentally accessible.  相似文献   

20.
Hormone-sensitive lipase (HSL), the enzyme controlling the rate of adipose tissue lipolysis and also possibly involved in the regulation of steroidogenesis, has been purified from bovine omental adipose tissue. Partially detergent-solubilized, delipidated and purified HSL was obtained through step-elution at conventional DEAE ion-exchange chromatography, followed by concentration on hydroxylapatite. High performance hydrophobic interaction chromatography (HPHIC) on phenylsilica then resulted in an increase of HSL protein purity from 2% to more than 70%. Final purification of the enzyme to apparent homogeneity (greater than 95% protein purity), concentration and removal of most of the detergent was obtained by high performance cation exchange chromatography on Mono S. At least 0.5 mg of highly stable HSL was obtained from 5 kg of bovine omental fat within four working days. The purified lipase had a lower specific activity than previously reported for the corresponding rat enzyme but the preparations have proved very useful for enzyme structure studies and as an antigen.  相似文献   

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