Site-directed mutagenesis of the Asp-197 and Asp-202 residues in chitinase A1 of Bacillus circulans WL-12.

The contribution of the Asp-197 and Asp-202 residues in chitinase A1 of Bacillus circulans WL-12 to the catalytic reaction was studied by site-directed mutagenesis of these residues. A kinetic analysis of the purified mutant chitinases suggests the involvement of both the Asp-197 and Asp-202 residues in the catalytic events of this enzyme, although the effects of mutations of Asp-197 were less severe than those of the other mutations.