Activation and stabilization of Candida antarctica lipase B in choline chloride-glycerol-water binary system via tailoring the hydrogen-bonding interaction.

As a new generation of green solvent, the utilization of natural deep eutectic solvents (NADESs) in enzymatic reactions has attracted widespread academic and industrial interests. Especially, choline chloride-glycerol (C-Gly) has been extensively used in many green chemistry processes. In this study, a series of C-Gly-water binary systems with extremely low viscosity were successfully constructed, and the enzyme performance in these binary systems was measured. The results showed that Candida antarctica lipase B (CALB) can be activated up to 156.64 ± 8.12% (7832.00 ± 162.47 U/mL) (when the mole fraction (x(D2O)) of water was 0.3), and a relatively high recycle stability (90.12 ± 1.77%) can be maintained when the mole fraction of water was from 0.0 to 0.6. Moreover, the enzyme performance was also explored in enzymatic synthesis of lauroyl glycine, and the results were highly agreement with pNPP assay. Molecular interaction between CALB and NADESs was studied by molecular dynamics methods. When x(D2O) was 0.3, a balance between the structural rigidity and flexibility can be maintained, while the balance was destroyed when x(D2O) was increased up to 0.7. Moreover, we also found that both clusters and monomers of NADESs can maintain high activity and stability of Candida antarctica lipase B (CALB). Therefore, this approach could provide a platform for the further utilization of NADESs in enzymatic reactions.