title: Enhanced enzyme activity and enantioselectivity of lipases in organic solvents by crown ethers and cyclodextrins.
abstract: Lipases from Candida rugosa (CRL) and Pseudomonas cepacia (PCL) were co-lyophilized with cyclic oligoethers including four crown ethers and nine cyclodextrins (CyDs), and their transesterification activity and enantioselectivity in organic solvents were evaluated. The PCL co-lyophilized with each additive showed simultaneously enhanced enzyme activity and enantioselectivity when compared to the native lipase lyophilized from buffer alone; in contrast, such enhancement was not observed for the co-lyophilized CRL. Among the cyclic oligoethers examined, permethylated betaCyD (Me1.78betaCyD), as the most suitable additive, was used for the optimization of both the co-lyophilized PCL preparation and reaction conditions by determining the effects of varying the additive/lipase ratio, aqueous pH, the nature of organic solvents, and temperature. The initial rate determined for the transesterification between racemic 2,2-dimethyl-1,3-dioxolane-4-methanol and vinyl butyrate in diisopropyl ether at 30 degrees C increased by up to 17-fold and the enantioselectivity represented by E could be doubled. While there was an inverse correlation between temperature and enantioselectivity, with the Me1.78betaCyD-PCL co-lyophilizate, the reaction rate even at 0 degrees C was much higher than that at higher temperatures in the native PCL-catalyzed reaction. Hence, this method seems to be of practical use for the large-scale production of optically active compounds.
authors.affiliation: Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611, Japan.
authors.forename: Yurie
authors.initials: Y
authors.lastname: Mine
authors.forename: Kimitoshi
authors.initials: K
authors.lastname: Fukunaga
authors.forename: Kyoko
authors.initials: K
authors.lastname: Itoh
authors.forename: Makoto
authors.initials: M
authors.lastname: Yoshimoto
authors.forename: Katsumi
authors.initials: K
authors.lastname: Nakao
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Sugimura