Preparation of glucose oxidase immobilized in different carriers using radiation polymerization

Glucose oxidase (EC 1.1.3.4) was immobilized on different polymeric materials using different immobilization techniques (entrapping by γ‐irradiation, and covalent binding using epichlorohydrin). Studies were carried out to increase the thermal stability of glucose oxidase (GOD) for different applications. The activity and stability of the resulting biopolymers have been compared with those of free GOD. The effect of different polyvinyl alcohol/polyacrylamide (PVA/PAAm) compositions of the copolymer carrier on the enzymatic activity of the immobilized GOD was studied. The maximum enzymatic activity was obtained with the composition ratio of PVA/PAAm of 60:40. The behaviour of the free and immobilized enzyme was analysed as a function of pH. A broadening in the pH profile (5.5–8) was observed for immobilized preparations. The activity and stability of the resulting biopolymers produced by immobilization of GOD onto different carriers have been compared, in both aqueous and organic media, with those of the free GOD. The enzyme's tolerance toward both heat and organic solvent was enhanced by immobilization onto polymers. The addition of different concentrations of organic solvents (10–50%, v/v) to the enzyme at higher temperature (60 °C) was found to stabilize the enzyme molecule. The strongest stabilizing effect on the enzymatic activity was achieved at a concentration of 10%. Copyright © 2005 Society of Chemical Industry     

Large deformation and ultimate properties of biopolymer gels: 2. Mixed gel systems

Biphasic, mixed gels of agarose and gelatin were prepared, and their mechanical behaviour in tensile tests was determined, up to failure, utilising four decades of (constant) strain rate. The behaviour of pure agarose and pure gelatin in such tests has been determined previously. Suitable ‘blending-laws’ relating the small deformation shear modulus of the composite to the moduli of the component phases have also been discussed elsewhere. This report extends the latter treatment to the more aggressive large deformation regime, deriving bounds for modulus and break stress which closely model observed behaviour.     

双水相分离提取胃蛋白酶和琼脂糖的初步研究

以聚乙二醇/硫酸钠双水相体系分离提取琼脂糖和胃蛋白酶.结果表明:琼脂糖的回收率高于90%,胃蛋白酶的回收率约为50%,两者最适宜的分离条件为:pH值为3,Na2SO4浓度为0.4 g·mL-1,PEG10000的浓度为0.002 mol·L-1.     

多肽配基亲和吸附介质的配基密度控制规律

以谷胱甘肽为配基,琼脂糖微球为骨架,探索将谷胱甘肽通过共价键偶联到琼脂糖微球骨架上,制备可以分离谷胱甘肽S转移酶(Glutathione S-transferase, GST)及以其为标签的融合蛋白的亲和吸附介质.采用正交实验方法考察了谷胱甘肽加入量、偶联缓冲液的pH值和反应温度对亲和介质配基密度的影响.结果发现,该反应过程中的pH值对配基密度影响最大,其次为谷胱甘肽的加入量.用所制备的亲和吸附介质纯化GST(大鼠肝脏谷胱甘肽S转移酶),发现GST的吸附量随配基密度增加而增加,但GST活性却随配基密度的增加而下降,较好的干胶配基密度为260 μmol/g.大鼠肝匀浆液经过离子交换和亲和层析两个步骤,获得了电泳纯的GST,比活力为12.08 U/mg,总活性回收率为40%以上.     

建立一种快速检测坂歧肠杆菌的方法

目的:建立快速检测婴儿配方奶制品(IFM)中坂歧肠杆菌的方法。方法:选择ATCC坂歧肠杆菌标准株,对不同的增菌性培养基、选择性培养基和显色培养基进行研究;结合VITEK仪和API20E细菌鉴定系统,构建快速检测配方奶制品中坂歧肠杆菌的方法。结果:建立的快速检测配方奶制品中坂歧肠杆菌的方法,所需检验流程为72h,方法灵敏度为2CUF/g,能有效区别于阴沟杆菌、产气杆菌等肠杆菌科细菌;方法应用稳定;操作简单、方法可靠,适宜规模化检测。结论:本研究认为,所建立的快速检测配方奶制品中坂歧肠杆菌的方法适宜检验检疫的工作要求,能有效地发现配方奶制品中坂歧肠杆菌的污染情况。     

壳聚糖-琼胶复合微球的制备及其药物释放性能

采用小分子离子交联法制备了pH值敏感的壳聚糖-琼胶复合微球,对壳聚糖-琼胶复合微球的粒径、形貌、pH值敏感性等进行了表征.以茶碱为模型药物研究了壳聚糖-琼胶复合微球的药物释放性能,结果发现一定量琼胶的引入有助于改善壳聚糖微球的药物缓释性能.     

葡聚糖接枝型高载量金属螯合介质的制备与性能

对琼脂糖凝胶微球进行烯丙基活化,再接枝葡聚糖分子,考察葡聚糖分子量等因素对葡聚糖接枝过程的影响;以葡聚糖接枝琼脂糖凝胶微球为基质,制备亚氨基二乙酸型金属螯合介质,考察葡聚糖接枝过程对金属螯合介质的孔道结构、流通性能和载量等的影响. 结果表明,分子量20~500 kDa的葡聚糖都能均匀分布于琼脂糖凝胶微球内,葡聚糖接枝量随分子量增加而增大,所制的金属螯合介质形貌、粒径及其分布基本不受影响,且具有更好的流通性能,孔道结构比商品介质Ni Sepharose 6FF更丰富. 葡聚糖接枝的金属螯合介质对带组氨酸标签的乳酸脱氢酶和睫状神经营养因子的载量分别达到19和27 mg/mL,较Ni Sepharose 6FF的载量分别提高26.6%和42.0%.     

低功率激光对大白兔血清LDL含量影响的实验研究

目的探索低功率氦氖激光对大白兔血液LDL含量的影响。方法大白兔分实验组与对照组,以波长为632.8nm,功率密度为5.4mw/cm2氦氖激光照射实验组大白兔,每天20分钟,连续照射10天。用血清脂蛋白琼脂糖凝胶电泳法测定实验组与对照组HDL、LDL、VLDL的含量。结果两组大白兔LDL水平有明显差异。结论低功率氦氖激光能明显降低大白兔血清LDL的水平。     

SH2020型全自动琼脂糖凝胶电泳系统在地中海贫血筛查中的应用

探讨SH2020型琼脂糖凝胶血红蛋白电泳在地中海贫血(地贫)筛查中的应用价值.方法:对2275例育龄人群、婚检和门诊患者应用北京金桑特SH2020全自动电泳分析系统进行血红蛋白电泳,通过自动扫描系统分析,检测Hb各组分的含量,初步分为属于α地贫或β地贫,再通过基因诊断确诊.在2275例中,通过血红蛋白电泳对HbA2异常者640例,进一步分为α地贫表型阳性412例,β地贫表型阳性186例.基因诊断结果显示,α地贫初筛符合率82.0%,β地贫初筛符合率90.3%.结果表明,SH2020型全自动琼脂糖凝胶血红蛋白电泳仪分辨率高,能够定量检测HbA、HbF、HbA2、CA含量,将地贫进行初步分类为α地贫或β地贫,有效地筛查出高危夫妇,并能够分辨出极微量异常Hb,为进一步进行基因诊断和遗传咨询提供准确可靠的数据.     

琼脂糖凝胶微球活化度的考察

琼脂糖凝胶微球广泛用于蛋白质的纯化,其活化度越高,能嫁接的亲和配基越多,纯化效率就越高。本文首先以反相乳液悬浮法制得琼脂糖微球,研究了琼脂糖活化反应中氢氧化钠、环氧氯丙烷、硼氢化钠的浓度及反应时间对活化度的影响,得到最佳活化条件。在此基础上,探索了不同粒径的琼脂糖微球对活化度的影响,表明凝胶微球粒径越小,活化度越高。