Study On The Immobilization Of Glucose Oxidase

According to the important function and the great significance in the industrial production of glucose oxidase(GOD),the article studied the immobilization technique of GOD.The economic,safe,nontoxic and best carriers were selected from some kinds of carriers which have different performance.The immobilized ways were studied and the conditions for immobilization were optimized.The immobilized enzymes were comprehensivly and systematically characterized in terms of their catalytic activity.At last,the properties of immobilized enzyme treatment on glucose solution were studied.Specfic research contents and results show that:Using the immobilized enzyme activity,enzyme activity recovery,shape of immobilized gel particles,and the factors such as economic,safe and nontoxic of carries as index,a single material(sodium alginate,chitosan,gellan gum,polyvinyl alcohol,ion exchange resin,activated carbon,gelatin,agar,agarose,polyacrylamide gel and carboxymethyl cellulose)was screened,finally preliminary screening gellan gum,sodium alginate,gelatin,agar,polyvinyl alcohol and chitosan.Sodium alginate as the basic carrier,respectively,adding gellan gum,gelatin,agar,polyvinyl alcohol and chitosan into sodium alginate,early selecting better composite carriers which were sodium alginate-gelatin and sodium alginate-gellan gum.The thermal stability,storage stability and operation stability of these two kinds of composite carriers were researched,finally screening alginate-gelatin as immobilized enzyme carrier.Using the immobilized enzyme activity and enzyme activity recovery as index,immobilized methods(direct embedding method,embedding crosslinking and crosslinking embedding method)and the immobilized way of catalase(CAT)such as not fixed,fixed GOD alone and double fixed were studied,the best immobilized way were direct embedding method and double fixing GOD and CAT.The conditions of immobilized glucose oxidase using sodium alginate and gelatin as carriers were studied,the best immobilized conditions were as follows:water of phase,the concentration of sodium alginate,CaCl2 solution,glucose oxidase were 2%,6%,1.0%,respectively.The ration of sodium alginate and gelatin,and GOD/CAT were 8:1 and 6:1.The immobilized time,temperature and pH were 30min,28? and 6.0.The immobilized enzyme activity recovery was 85.76%,demonstrated a good reusability for it was able to maintain more than 32%of its activity after seven cycles of operation.The optium temperature and pH of free enzyme and immobilized enzyme catalysis reaction were 35?,5.5 and 6.0,respectively.There was a wide range of temperature and pH in immobilized enzyme,it showed immobilized enzyme had better temperature and pH adaptability and stability.Immobilized enzyme had better thermal stability and storage stability than free enzyme.The michaelis-menten constant of immobilized enzyme and free enzyme were 11.18×10-2 mol/L and 23.32×10-2mol/L,this showed the affinity between immobilized enzyme and substrate was smaller.The influence of metal ions to free enzyme was smaller,but the inhibition effect was bigger on immobilized enzyme.In addition to methanol,the influence of organic solvents to immobilized enzyme was smaller than the free enzyme.The result of immobilized enzyme treatment on glucose solution showed that:a great enzyme activity was observed with inoculation quantity of 8%-10%using 180rpm of shaking speed and 25%of glucose solution concentration,the whole process need to constantly adjust pH by adding NaOH to solution.The residual glucose concentration was 1.10%after 10h of enzyme catalysis reaction for free enzyme,glucose conversion rate was approximately 98%;but immobilized enzyme had only 52%of glucose conversion rate after 10h enzyme catalysis reaction.