Challenges in the directed evolution of stereoselective enzymes for use in organic chemistry

Directed evolution constitutes an ideal method for engineering essentially any catalytic parameter of enzymes for application in synthetic organic chemistry and biotechnology, including thermostability, substrate scope and enantioselectivity. Stereoselectivity is especially important when applying biocatalysts to synthetic organic chemistry. This article focuses on recent methodology developments in laboratory evolution of stereoselective enzymes, hydrolases and monooxygenases serving as the enzymes. Iterative saturation mutagenesis (ISM) has been developed as an unusually effective method to evolve enhanced or reversed enantioselectivity, broader substrate scope and/or higher thermostability of enzymes.