FIG. 3.

Thermostability of wild-type MtL expressed in the yeast S. cerevisiae and in A. oryzae, and of two mutants found in generation 9. Mutant 8H9 was discovered with the stability screen, and 3A6 was discovered with the activity screen. Tubes containing 50 μl of B&R buffer (10 mM; pH 6) containing 0.3 U of enzyme activity/ml were incubated at various temperatures and assayed for residual activity after 0, 1, 7, and 24 h at 23°C with ABTS as substrate. The activities were normalized to the initial activity at 23°C before the incubation.