Enhancing protease enantioselectivity by ionic liquids based on chiral- or ω-amino acids

Ionic liquids (ILs) carrying anions of chiral- or omega-amino acids were prepared. The enzymatic hydrolysis of phenylalanine methyl ester was studied in aqueous solutions of these ILs. These ILs were found capable of stabilizing the protease activity and enantioselectivity at low concentrations. Interestingly, higher ees and yields Of L-phenylalanine were generally observed in ILs based on D-amino acids rather than in those derived from L-isomers. The reason could be that D-amino acids are more kosmotropic than L-isomers. Meanwhile, the IL-D2O solution was able to further enhance the enzymatic resolution, when comparing with that in an IL H2O system. (c) 2006 Elsevier Ltd. All rights reserved.