Fig. 8

Total interaction energy between the substrate and each protein residue. Energies are averaged over the length of the MD simulations. The CcCBM17 (top) and BspCBM28 (bottom) residue numbers are shown along the x-axis. The simulation case label is given at left, four cases for each family 17 and 28 CBM. The magnitude of the interaction energy between a given residue and the bound ligand, as indicated in the case name, is shown in white-red-black gradient. Favorable interactions are more negative and, thus, darker/black. In cellopentaose binding, ligand direction does not affect CBM–cellopentaose interactions, as redundant protein residues along the binding groove maintain an association with cellopentaose. In non-crystalline cellulose binding, the CBM protein surface interacts with the surrounding carbohydrate, in both forward and reverse orientations, to enhance binding affinity; the new protein–carbohydrate interactions are unique for each CBM and each direction