Property of Taka-amylase A with Glu or Asp of the Catalytic Residue Replaced by the Corresponding Amine

Compared with the enzyme activity of a recombinant Taka-amylase A (wild TAA) at 25°C and pH 5.3, those of two mutants (E230Q and D297N) were 1/10,000 and 1/16,000 for amylase activity, and 1/920 and less than 1/20,000 for maltosidase activity, respectively. This indicates that all residual activities of E230Q are not due to contamination by wild-type TAA. The results from difference spectroscopy suggested that E230Q retains amylose binding ability.