How can aprotic ionic liquids affect enzymatic enantioselectivity?

Hidetaka Noritomi, Hideki Chiba, Manabu Kikuta, Satoru Kato

Dai-Ichi Kogyo Seiyaku Co., Ltd., Oogawara-cho, Kisshoin, Kyoto, Japan.
Department of Applied Chemistry, Tokyo Metropolitan University, Tokyo, Japan.

DOI: 10.4236/jbise.2013.610117                

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_catK_M)_L/(k_cat/K_M)_D ratio in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([C₂mim][FSI]) containing 1.0% (v/v) water at 25°C exhibits 32,000, while that in 1-ethyl-3-methylimidazolium tetrafluoroborate ([C₂mim][BF₄]) containing 1.0% (v/v) water at 25°C shows 190. The (k_cat/K_M)_L/(k_cat/K_M)_D ratio in [C₂mim] [BF₄] 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)

Keywords

α-Chymotrypsin; Enantioselectivity; Esterification; Aprotic Ionic Liquid

Conflicts of Interest

The authors declare no conflicts of interest.

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