CROWN-ETHERS AS REGULATORS OF ENZYMATIC-REACTIONS - ENHANCED REACTION-RATE AND ENANTIOSELECTIVITY IN LIPASE-CATALYZED HYDROLYSIS OF 2-CYANO-1-METHYLETHYL ACETATE

Both reaction rate and enantioselectivity in lipase-catalyzed hydrolys is of 2-cyano-1-methylethyl acetate were significantly changed by addi tion of some crown ethers. Although various crown ethers accelerated t he reaction rate, the enantioselectivity greatly depended on the natur e of each one. Among 27 crown ethers and 5 polyethers tested, benzo-cr own, armed azacrown, and thiacrown ethers offered high enantioselectiv ity of the lipase-catalyzed hydrolysis. Hydrophobicity and chirality o f the crown ether did not affect the hydrolysis behavior, but its conc entration greatly influenced enantioselectivity. Two hundred fifty or more times the crown ether, molarity based on the enzyme, was required to attain satisfactorily high reaction rate and enantioselectivity.