Comb-shaped poly(ethylene glycol)-modified subtilisin Carlsberg is soluble and highly active in ionic liquids. 
Subtilisin Carlsberg conjugated with comb-shaped poly(ethylene glycol) was solubilized in common ionic liquids without adding water, and exhibited higher transesterification activity in an ionic liquid, [Emim][Tf2N], than in organic solvents commonly used for enzymatic biotransformation.