Computer-Aided Tunnel Engineering: A Promising Strategy for Improving Lipase Applications in Esterification Reactions

Esterification is one of the most important reactions in organic synthesis and industrial applications. The applications of lipases in esterification are increasingly widespread and have high cumulative values. Mostly, in the catalytic cycle of lipases, the tunnel connecting the active site to the surface of a protein plays a significant role in ligand transport. As a unique conformational structure of a protein, the tunnel could regulate the catalytic performance of lipases via ligand transportation. Therefore, the tunnel of lipase can be designed accordingly to speed up the transportation of the ligand, also highlighting the importance of tunnel engineering in the industrial application of enzymatic esterification reactions. This article reviewed the characterizations of the tunnel structure and focused on the strategies of tunnel engineering, such as rational design and directed evolution. Additionally, tunnel engineering using computer-aided design techniques (e.g., CAVER, Molecular Dynamics simulations) to improve the catalytic functions of lipases, such as activity, substrate specificity, and stability, was also discussed in depth. Finally, this review provides future perspectives about tunnel-engineered lipases as biocatalysts in esterification reactions.