Preparation Of Chitosan Resin And Its Immobilization On Lipase

The technology of immobilized enzyme can maintain the activity of the enzyme and reuse of thecharacteristics; it is concerned by many researchers. The key of immobilization technology is tochoose the right carrier, the immobilization methods and conditions. As free lipase has high catalyticactivity, it’s widely used in the field of food, medicine, and chemical and so on, but the drawback isthat it is hard to separate the lipase from the product, and the lipase can not be reused. Theimmobilization of enzyme can be a good solution to this problem.For that reason, the experiment is to develop an immobilized lipase with chitosan resin as thecarrier, then explore its enzymatic properties, and finally straightly modify the chitosan resin.With chitosan as raw material, formaldehyde as pre-cross-linking agent, glutaraldehyde as crosslinking agent, chitosan resin by suspension cross linking agent was prepared. The result of FTIR,XRD and DSC showed that the cross linking reaction took place between the amino groups ofchitosan and aldehyde groups of glutaraldehyde to generate the Schiff structure, further to form thechitosan beads， besides, the processed chitosan has lower crystallization ability and thermal stability.Chitosan resin immobilized lipase was prepared by coupled lipase with chitosan resin as carrierand epichlorhydrin as activator. The result shows when the concentration of NaOH arrived at1mol/L,the content of epichlorohydrin arrived at0.8ml, activating temperature at60°C and couplingtemperature at40°C, the prepared resin-lipase obtained the higher lipase coupling capacity. After thelipase was immobilized on chitosan-resin, protein peptide chain’s folding and winding was obstructed,three-dimensional structure of lipase had been effectively protected and had quit well tolerance ability,what’s more, it kept good catalytic activity in higher temperature and a wide range of the pH(6.5-10.5).The optimum reaction temperature of immobilized lipase was50°C,10°C higher than the free enzyme,and its optimum pH is7.5, while the free enzyme is8.5. The storage stability and operational stabilityof immobilized lipase were greatly improved.Chitosan resin microspheres with different size of the aperture were prepared with differentamounts of porogen, and that resulted in different adsorption properties. It showed that polyethyleneglycol-4000(PEG) porpgen had better porogenic effect than distilled water and ethyl acetate, butmechanical strength of the resin decreased at the same time. In view of this, polyvinyl alcohol PVA was added to the resin. The result showed that the resin not only had better mechanical strength, butalso ensured a certain degree of protein adsorption capacity.