FIG. 5.

(A) pH-activity profiles of wild-type (wt) MtL expressed in S. cerevisiae, wt expressed in A. oryzae, and of mutants 37A7 (generation 7), 8H9 (stability mutant, generation 9), 3A6 (activity mutant, generation 9), and T2 (generation 10). Activities were measured in B&R buffer at different pHs with ABTS as substrate. Laccase activity is normalized to the optimum activity value of the enzymes. (B) Stability of MtL wild type and mutants at pH 3. Enzyme samples (0.3 U/ml) were incubated in B&R buffer, pH 3, and residual activity at pH 6 was measured with ABTS as substrate. The activities were normalized to the initial activity at pH 6 before the incubation.