Optimised Protocol for Drying Aqueous Enzyme Solutions in Organic Solvents – Comparison of Free and Immobilised Candida antarctica Lipase B

• Published in: ChemCatChem
• Main Authors: Tjørnelund, Helena D., Brask, Jesper, Woodley, John M., Peters, Günther H.J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: Antarc*; Antarctica
• Online Access: https://orbit.dtu.dk/en/publications/387250a5-88d4-4eb9-a2fa-1929e1bcbdd6; https://doi.org/10.1002/cctc.202201207; https://backend.orbit.dtu.dk/ws/files/304333369/ChemCatChem_2022_Tj_rnelund_Optimised_Protocol_for_Drying_Aqueous_Enzyme_Solutions_in_Organic_Solvents_Comparison_1_.pdf

Here, we propose an optimised protocol for controlling the initial water activity (aw) in organic reaction mixtures with soluble lipase to ensure reproducible and consistent enzyme activity measurements. Pre-equilibration above saturated salt solutions was used to set aw of the reaction media, where aw was tracked with a hygrometer. Consistent stirring of the suspension and volume correction to compensate for solvent evaporation were found to be critical. The protocol was tested on Candida antarctica lipase B (CALB) in soluble and immobilised forms in three organic solvents (acetonitrile, methyl tert-butyl ether, and hexane) at four different water activities ranging from 0.12 to 0.97. Soluble and immobilised CALB had similar aw-profiles and showed the highest enzyme activity in hexane. The optimised protocol expands the possibility to study enzyme kinetics from immobilised enzymes to soluble enzymes.