Solvent-accessible cavities in wild-type acetate kinase and the modeled Val93Ala and Val93Gly variants. (A, C, and E) Wild-type acetate kinase and the Val93Ala and Val93Gly variants, respectively, with the active site cavity volume masks. (B, D, and F) Acetate, propionate, and butyrate modeled into wild-type acetate kinase and the Val93Ala and Val93Gly variants, respectively. All diagrams were generated by using MOLSCRIPT (20) and Raster3D (25).