Transesterification of a Tertiary Alcohol by Engineered Candida antarctica Lipase A.

Tertiary alcohols are known to be challenging substrates for applications in asymmetric synthesis due to their complexity and steric hinderance. The occurrence of tertiary alcohols and their esters in nature indicates the presence of natural biocatalytic synthetic routes for their preparation. Lipase A from Candida antarctica (CalA) is a hydrolase that has previously been shown to catalyze the transesterification of racemic 2-phenylbut-3-yn-2-ol at a low rate. In this work, the activity of that enzyme was improved by protein engineering through a semi-rational design strategy. An enzyme library was created and screened for transesterification activity towards racemic 2-phenylbut-3-yn-2-ol in an organic solvent. One successful enzyme variant (L367G) showed a tenfold increased reaction rate compared to the wild-type enzyme, while maintaining a high enantioselectivity.