Low resolution crystal structures of Taka-amylase A and its complexes with inhibitors.

The molecular structure of Taka-amylase A, an alpha-amylase from Aspergillus oryzae, has been studied at 6 A resolution by X-ray diffraction analysis. The electron density map showed a non-crystallographic three-fold screw arrangement of the molecules in the crystal. The molecule is an ellipsoid with approximate dimensions of 80 x 45 x 35 A and contains a hollow which may correspond to the active center. The inhibitor molecules bind to Taka-amylase A at four different sites, one of which is located in the hollow of the enzyme. The probable position of a thiol group is discussed in connection with heavy atom binding.