Protein engineering of cellulase enzymes for enhanced binding to single-walled carbon nanotubes: a computational approach to enzyme recycling in biofuel applications

Cellulases serve as essential biocatalysts in the industrial conversion of cellulosic biomass into bioethanol. Immobilizing these enzymes on carbon nanotubes (CNTs) enhances their recyclability, offering a promising strategy for cost-effective biofuel production. This study investigates the structural dynamics and binding stability of CNT-immobilized cellulases from bacteria and fungi (Cel6A, Cel7A, Cel7D, Cel48F, and CelS) in both wild-type (WT) and the computationally engineered or mutant-type (MT) variants. Initially, molecular docking and network analysis were employed to identify optimal CNT-binding domains in WT enzymes. Targeted mutations, specifically hydrophilic-to-tryptophan substitutions, were introduced in the CNT-binding domain of WT enzymes to enhance π–π interactions between the enzymes and CNTs. Subsequently, molecular dynamics simulations were performed under physiological conditions. We observed that MT enzymes exhibited stronger CNT binding than WT enzymes while maintaining catalytic functionality, with minimal deviation from their native structures. These findings provide valuable insights into enzyme immobilization strategies, enabling the design of biocatalysts for industrial bioprocessing, materials science, and biomedical applications.