Molecular dynamics study of carbohydrate binding module mutants of fungal cellobiohydrolases

The present study reports the systematic survey of binding free energies at the interface between a carbohydrate-binding module (CBM) and a cellulose Iα crystal model using molecular dynamics' calculations. The two wild type CBMs (Cel7A CBM and Cel6A CBM) have been studied, as well as seven mutants of Cel7A CBM. A comparison of the experimental data for the two wild type and the four mutants CBMs (i.e., Y5A, Y5W, N29A, and Q34A) revealed that the interaction energies of Y5W and Q34A were larger than that of the wild type Cel7A CBM, whereas Y5A and N29A gave smaller values. These predicted values of the interaction energies were compared with the results observed for the adsorbing behaviors of the CBMs.