Figure 5: The roles of surface aromatic residues.
(a) Stick representation of the surface aromatic residues (magenta) of AmyPΔSBD (blue on the left) and the surface aromatic residues (orange) of barley α-amylase AMY1 (pdb accession code 1RP8, light orange on the right). Saccharide bound in the active site cleft of AmyPΔSBD is shown as yellow sticks. Saccharides bound in the active site cleft and at surface sites of AMY1 are represented by green sticks. In both structures, the catalytic residues are shown in red and calcium ions are shown as hot pink spheres. (b) Surface representation of AmyPΔSBD (left) and barley α-amylase AMY1 (right). (c) Comparison of the specific activities of WT AmyPΔSBD, its W80A, Y228A, Y252A, and W272A single point mutants (left) and its W80A/Y228A, Y252A/W272A, W80A/Y228A/Y252A, and W80A/Y228A/Y252A/W272A multiple point variants (right) using soluble rice starch and insoluble rice starch, respectively, as substrates.
