The Catalytic Characteristics Of Lipase Immobilized With No Carrier

Lipase is a kind of efficient and environmentally friendly biocatalyst,which is widely used in varieties of fields.However,free lipase has lots of disadvantages,such as insufficient stability,difficulty to recovery and reuse,and etc.Therefore,it is limited in industrial application.In order to improve the stability and reusability of lipase in pratical application.Bovine pancreatic lipase was used as a model system,Cross-linked enzyme aggregates of lipase(Lipase-CLEAs)and Lipase-CLEAs with BSA(BSA-lipase-CLEAs)were prepared by the cross-linked enzyme technology.Cu3(PO4)2-enzyme-inorganic hybrid nanaflowers using Cu3(PO4)2 as the inorganic component and lipases as the organic component.1)Preparation condition of Lipase-CLEAs and It's propertiesThe saturation concentration of precipitant,cross-linking agent concentration and the cross-linking time were optimized By one-factor-at-a-time experiments.The optimized conditions were as follow: final saturability of the ammonium sulfate is 80%,final concentration of glutaraldehyde is 1.5 %,and corss-link time is 1 hour.Under Optimized condition,the highest activity recovery of lipase was obtianed.In addition,compared to free lipase,the optimum temperature of Lipase-CLEAs is 60?,which is increased about 10 ?.The thermal stability,pH stability,operational stability,and storage stablility of Lipase-CLEAs were significantly enhanced compared with free lipase.Furthermore,the Lipase-CLEAs still retained 40% of its initial activity after consecutive 7 cycles.2)The Effects of bovine serum albumin(BSA)on(lipase-CLEAs)and it'spropertiesThe mass concentration of BSA,the saturation concentration of depositing anget,the mass concentration of cross-linking agent and the cross-linking time were optimized by the method of single factor.The optimized conditions were as follow: The mass concentration of BSA,0.05g/L;the mass concentration of glutaraldehyde 1%;the final saturability of the ammonium sulfate 80%;cross-linking time 2 h.Compared with Lipase-CLEAs,the activity recovery of BSA-lipase-CLEAs was increased by 15%.The optimal temperature of BSA-lipase-CLEAs was increased by 10 ? compared with free lipase.In addition,the BSA-lipase-CLEAs showed more excellent properties in pH,thermal and storage stability than that of free lipase and the Lipase-CLEAs.Moreover,the BSA-lipase-CLEAs still retained 80% of its initial activity after consecutive 7 cycles.However,the Lipase-CLEAs only still retained 30% of its initial activity.3)The preparation of enzyme-inorganic hybrid nanoflowers using Cu3(PO4)2 as the inorganic component and lipases with activation as the organic component and it's properties.Lipase concentration,the copper sulfate concentration and surfactant concentration were optimized.The optimized preparation conditions: The concentration of Cetyl trimethyl ammonium bromide is 0.25 mmol/L,the concentration of lipase is 0.025g/L,the content of 120 mmol/L copper sulfate in 300 ml phosphate buffer(pH7.4,100 mmol/L)is 2 mL.Under optimized condition,the activated nanoflower exhibited 460% and 200% higher activity than native lipase and conventional lipase-inorganic hybird nanoflower,respectively.After consecutive 7 cycles,the actived nonoflower still retained 100% of its initial activity.