Fig. 8

Crystal structure analysis of TwCel5_CAT. A Orthogonal view of the TwCel5_CAT tertiary structure showing the characteristic (β/a)₈-barrel fold. Helices are blue, β-strands cyan, and loops white are shown. Mg²⁺ and K⁺ ions are shown as green- and purple-colored spheres, respectively. B The putative active site of TwCel5_CAT, with the side chains of Glu157 and Glu245 shown with yellow carbons. C Illustration of substrate binding groove with the side chains of amino acids potentially interacting with substrate shown with blue carbons. For illustration purposes, a thiocellopentaose molecule has been placed in substrate binding site by structural superposition of TwCel5_CAT structure with the structure of ligand containing Cel5A from Bacillus agaradharens (PDB identifier: 1H5V). D Structural superposition of subsite defining amino acids of TwCel5_CAT and B. agaradharens Cel5A, highlighting the putative + 3 subsite in TwCel5_CAT. TwCel5_CAT, blue carbons; Cel5A, grey carbons; substrate, green carbons