3.2. Immobilization of laccase
As shown in Fig. 2, the maximal activity recovery (91.0%) of the
immobilized laccase was obtained when the initial laccase concentration
was 0.4 mg ml1, and the total activity reached its peak
value when the laccase concentration was 1.0 mg ml1. Although
the adsorbed amounts of laccase on CMMC increased with the augment
of the laccase concentration, the trends of activity recovery
and total activity decreased when the laccase concentration was
above 0.4 mg ml1 and 1.0 mg ml1, respectively. Similar phenomenon
was also reported in the study of laccase immobilization on
magnetic mesoporous silica nanoparticles as a function of laccase
concentration (Wang et al., 2010a). Excessive laccase adsorption
would easily result in the crowding or agglomeration of enzyme
molecules inside the mesopore channels and at the other active
sites of the carrier. Thus the resulting steric constraints could subsequently
restrain the dispersion and transmission of the substrate
and product, exhibited as the reduction of activity.