【作者】 丁宇；

【导师】 李正强；

【作者基本信息】 吉林大学 ， 生物化学与分子生物学， 2006， 硕士

【摘要】 在通常条件下,酶表现出较高的活性和专一性。但是,温度、压力、电磁场、有机溶剂、金属离子、离子强度、pH和变性剂,都容易导致酶的变性或者失活。因此,为了增大这些生物催化剂的应用范围,在合适的支持物上面固定化酶这项技术得到了发展。最近,固定化酶已经得到广泛地应用,而且不同种类的固定化载体支持物也已经被大量的应用。但是,将酶固定化于无机或有机的固定化载体中,固定化酶的活性往往很低。这是因为酶会从固定化载体上滤出,以及酶在催化反应时有效化学构象的转变被限制所造成的。在这里,根据“Fish-in-net”的观念,将胰蛋白酶固定化于规则有序的、中空多孔道分子筛的大孔径“网”中。这些“网”是通过统一的中空多孔通道相连接的,它们为酶蛋白分子的旋转和构象的转变提供了足够的空间,这对生物催化反应是非常有利的。同时,又对固定化胰蛋白酶的性质进行了进一步的研究,发现通过这种方法固定化的酶具有良好的稳定性、催化反应活性及重复利用度。更多还原

【Abstract】 The enzyme is a kind of protein with catalytic function .As a kind of biocatalyst, the enzyme participates every kindof metabolism of the living creature inside. Both its quantityand quality do not change after reactions. Enzyme can catalyzethe reaction effectively with high specificity in normaltemperature and atmospheric pressure under the gentlecondition (107-1013 times higher than general catalyst). Manyorganic chemical reactions which are difficult to go on canproceed successfully catalyzed by enzyme, and can reduce oravoid side reactions.However, the senior structure of enzyme consisting ofamino acid is very sensitive to the environment. Severalfactors can cause the inactivation of enzyme activity,including physical factor(temperature、atmospheric pressure、electromagnetic field)、chemical factor(oxidation、reduction、organic solvent、metal ion、ionic strength、pH value) andbiological factor (enzyme modification、enzyme degradation).Even if under the most comfortable reaction condition of theenzyme, the enzyme will be lost alive too, and the reactionspeed could drop gradually with the time extended. The enzymeis unable to be retrieved after reacting. All these give muchmore questions to the use of enzyme, and restrains enzymepharmaceutical product from use and development. So in orderto increase the range of application of this kind ofbiocatalyst, the technology of fixing enzyme on suitablesupport thing has developed.There is currently great interest in enzymeimmobilization to enhance enzyme stability and reusability,and to aid in separation from the reaction mixture, butimmobilized enzymes on commonly used inorganic and organicsolid supports show low activities. This is a result of theleaching of the enzymes from the solid supports and the limitedconformational transitions available to the enzymes forchemical interaction on the supports. Enzymes encapsulated bya sol-gel/polymers show good activity, but the wide pore-sizedistribution in sol-gel/polymers cannot be well controlled,and this adversely influences the diffusion of reactants andproducts during biocatalysis to the detriment of theirpractical application. Recently, a number of successfulexamples of good enzyme activity resulting from enzymeimmobilization in uniform mesopores of ordered mesostructuresmaterials have been reported. However, enzyme immobilizationin mesopores is limited by the pore size of the mesostructurematerials, so that bulky enzymes or enzyme aggregates largerthan the mesopores cannot be immobilized.Trypsin is a kind of protease of animal source. Thebiocatalyst of this kind modifies enzyme activity throughproteolytic function. Recently, trypsin shows the foregroundof use extensively, including the clarifying of the drinks andbeverage , the hydrolysis of domestic animal’s blood protein ,and the preparation of pancreas peptone . However, thestability of natural trypsin is bad . And because of thedegradation of trypsin itself , it makes the reactioncondition difficult to control . The efficiency of catalysisbecomes low, and the cost enhances.We depended the concept of “Fish-in-net” encapsulationof Trypsins in ordered mesoporous silica. This technique usedTrypsins as templates, the encapsulated Trypsins in themesoporous silica are nanoreactors, which combine theadvantages of native Trypsins with those of mesoporouschannels. So the chemical environment of the Trypsins in thecages is similar to that of native Trypsins in aqueous solution.This id beneficial for Trypsins rotation and conformationaltransitions, and provides for high biocatalytic activity.Encapsulated Trypsins was observed by scanning electronmicroscopy (SEM) and transmission electron microscopy (TEM) ,Trypsins are entrapped in macroporous “net” connected byuniform mesoporous channels, which is helpful for the fastdiffusion of reactants and products during the biocatalysis.And the ordered hexagonal mesopores around the macroporous“net” are gradually twisted, it is possible that the twistedmesopores are a factor that prevents leaching of the Trypsinsfrom the samples.This study compared the catalytic activity of fixedtrypsin with the natural trypsin under different conditions.We determined the rate of envelopment both fixed trypsin andnatural trypsin, the Optimum temperature and pH of envelopmentboth fixed trypsin and natural trypsin, the change of heatstability, the inhibition of substrate catalyzed by trypsinthrough Poly-L-Lysines of different mol. wt, the transformcontrast of substrate catalyzed by trypsin, and thedetermination of duplicated utilization of fixed trypsin.As a result, these encapsulated Trypsins show goodactivity, long-term stability, and excellent recyclingcharacteristics.更多还原