Immobilization of laccase on polyacrylamide and polyacrylamide – κ – carragennan-based semiinterpenetrating polymer networks

Abstract

In this study, laccase enzyme (L) from Agaricus bisporus was immobilized by entrapment into polyacrylamide (PAAm) and semi-interpenetrating polymer networks (semi-IPNs) prepared with either polyacrylamide/kappa-carragennan (0.05g) [PAAm/kappa-car (0.05)] or polyacrylamide/kappa-carragennan (0.1 g) [PAAm/kappa-car (0.1)]. The optimum pH was 6.0 for free L, 8.0 for PAAm-L, 8.5 for PAAm/kappa-car (0.05)-L, and 9.0 for PAAm/kappa-car (0.1)-L. The optimum temperature was determined as 45 degrees C for free L and 60 degrees C for all immobilized laccases. After 27 days of storage at 4 degrees C, free enzyme lost its initial activity whereas immobilized enzymes retained 56 % (-)80 % of their initial activities. The immobilized samples were used repeatedly 35 times by retaining 28 %-58 % of their initial activity. K-m(app) values were calculated as 0.088, 0.139, 0.133, and 0.131 mM and Vmax values were found to be 2.83 x 10(-3), 4.51 x 10(-3), 4.76 x 10(-3), and 4.97 x 10(-3) mM min(-1) for free L and PAAm-L, PAAm/kappa-car (0.05)-L, and PAAm/kappa-car (0.1)-L, respectively.