The open–close conformational change of aspartate aminotransferase.

The crystal structures of AST from S. pombe (cyan and pink) and S. cerevisiae (green and hot pink) were superimposed through the bottom of helix α12 (residues 310–322) for facilitating the comparison between their conformational changes. The three individual segments of each subunit are represented as follows: (A) the small domain shows rigid body rotation tilted from the boundary between the small and large domain; (B) the large domain shows a subtle conformational difference between the two structures; and (C) two structures are superimposed through their α1 helices for aiding the comparison between their N-terminal arms. (D) The structures of the cavities (dashed circle) in ASTs from S. pombe (left), S. cerevisiae (middle), and G. gallus (right) are represented via surface charges. The inhibitor maleate was modeled in the structure of S. pombe by superimposing with that of S. cerevisiae. (E) Hydrophobic inter-subunit interaction between α1 of the small domain and the large domain of a partner subunit are shown. Color representation is same as that of Fig 1A. Both the inhibitor and cofactor are represented as white stick, and the phosphate is shown as orange stick.