Study Of Laccase Immobilization On Cross-Linked Polyglycol Diacrylate And Its Performances

As a biocatalyst, free laccase can't meet with the requirement of modern industry. So finding out a new kind of material which can immobilize the free laccase efficiently is great important. Cross-linked polyglycol diacrylate is a kind of organic polymer, which is envirmental friendly and has a high water absorbency. It is a potentially useful carrier for enzyme immobilization.In this work a series of different molecular cross-linked polyglycol diacrylate carriers were synthesized. In addition, the effect of reaction conditions and the moleculars on immobilized laccase were also studied. Results showed that the cross-linked PEG (20000) DA is the best carrier. The factors that affected the relative activities of immobilized laccase were discussed, such as cross-linked time, cross-linked temperature and so on. When the cross-linking agent concentration was 0.5%, cross-linked temperature was 175℃and the reaction time was 30 minutes, the activity of immobilized laccase was the highest.The immobilization conditions were optimized, and it was found that the best immobilization time was 4 hours, with the adsorption time was 15 hours under 4℃, and the optimal ratio of carrier to laccase solution was about 30mL/0.1g carrier. The laccase immobilized on cross-linked PEG(20000)DA carrier showed the best activity at 60℃and in the buffer of pH 3.5. The K_m of immobilized laccase was 3.37×10^-4 mol/L and it was bigger comparing with free laccase. The loading capacity could achieve 0.792mg/g carrier. And the activity of immobilized laccase has achieved 54.57U/(g·min) with the immobilization efficiency being 54.3%. In other words, 1 mg laccase that owned by immobilized laccase can consume 68.90μmol ABTS.Moreover, the use stability, pH stability, staying and temperature stability were detected in this work. Results indicated that the reclaimed activity was 90% at the second use, and after six times'use it still kept 60%. The activity of immobilized laccase after 1h staying in buffer still kept 80% at the pH range of 3⁵. The activity of immobilized laccase after 20 days staying was not less than the fresh sample. And it had the best activity when treated under 70℃for 2 hours.At last, the immobilized laccase was used in the biocatalysis of 2,4-...