How can aprotic ionic liquids affect enzymatic enantioselectivity?

Abstract

The enantioselectivity of α -chymotrypsin in the esterification of N- acetyl-tryptophan with ethanol was examined in aprotic ionic liquids. The enantioselectivity was found to be strongly affected by a kind of solvent, water content, and reaction temperature. The ( k cat K M ) L /( k cat / K M ) D ratio in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([C 2 mim][FSI]) containing 1.0% ( v / v ) water at 25°C exhibits 32,000, while that in 1-ethyl-3-methylimidazolium tetrafluoroborate ([C 2 mim][BF 4 ]) containing 1.0% ( v / v ) water at 25°C shows 190. The ( k cat / K M ) L /( k cat / K M ) D ratio in [C 2 mim] [BF 4 ] at 25°C varies from 190 at 1.0% ( v / v ) water to 65000 at 5.0% ( v / v ) water. Moreover, the ( k cat / K M ) L / ( k cat / K M )