Diverse effects of aqueous polar co-solvents on Candida antarctica lipase B

Biocatalysis in mixtures of water and co-solvents represents an opportunity to expand the application of enzymes. However, in the presence of organic solvents, enzymes can undergo reversible inhibition, inactivation, or aggregation. In this work, we studied the effects of three co-solvents (methanol, acetone, and dimethyl sulfoxide - DMSO) on the function and structure of the recombinant Candida antarctica lipase B (rCALB), a widely used enzyme in biotechnological applications. The effects of co-solvents on rCALB were investigated by steady-state kinetics experiments, biophysical assays and by molecular dynamics simulations in the presence and upon incubation with the three co-solvents. Methanol and acetone were found to act as competitive inhibitors of rCALB and to promote its aggregation, whereas DMSO is a non-essential activator of rCALB.