Improved chemical and physical stability of laccase after spherezyme immobilisation

Laccase was successfully self-immobilised into particles using spherezyme methodology, with a retention of 53.9% of original enzyme activity. Post-treatment of the spheres with ethanolamine or a combination of polyethlyeneimine and ethanolamine reduced this to 49.4% and 23.3%, respectively. However, polyethyleneimine coated spherezymes displayed improved stability towards oxidative denaturation by mediators with improvements of 5.61-, 6.95- and 15.55-fold for 2-hydroxyphtalimide, N-hydroxybenzotriazole and 2,2,6,6-tetramethylpiperidinooxy free radical, respectively. The immobilised preparation displayed enhanced stability during temperature incubation at 60–70 °C with an improvement of 2.04- and 4.03-fold respectively for ethanolamine post-treated spherezymes and polyethyleneimine coated spherezymes. Furthermore, enhanced stability at acidic pH was observed, with the most pronounced enhancement of 2.49-fold obtained at pH 2, and 1.69 and 1.38 at pH 3 and 4, respectively.