Kinetic resolution of racemic alpha-methyl-beta-propiothiolactone by lipase-catalyzed hydrolysis.
Kinetic resolution of racemic alpha-methyl-beta-propiothiolactone (rac-MPTL) using lipases in organic solvent was studied. The lipase from Pseudomonas cepacia (PCL) showed the highest (S)-enantioselectivity (E > 100), and cyclohexane containing 1% (v/v) buffer was identified as the best reaction medium for maintaining high enantioselectivity as well as high reaction rate. While the substrate inhibition was not observed up to 300 mM rac-MPTL, severe product inhibition was observed even at 50 mM racemic 3-mercapto-alpha-methyl propionic acid (rac-MMPA), which made the use of high substrate concentration difficult. To overcome the product inhibition, the products, (R)-MMPA, were neutralized by addition of a dilute basic solution. Although the resolution reaction proceeded further by the base titration, the enantioselectivity of the reaction decreased as a result of nonenantioselective hydrolysis of rac-MPTL in the basic solution. Under these conditions, 200 mM rac-MPTL was successfully resolved to above 95% ee(S) with 53% conversion.
Hwang
B Y
BY
Division of Chemical Engineering, Institute for Molecular Biology and Genetics, Seoul National University, Seoul 151-742, Korea.
Lee
H B
HB
Kim
Y G
YG
Kim
B G
BG
D016956:Burkholderia cepacia / Q000201:enzymology; D002384:Catalysis; D006868:Hydrolysis; D007700:Kinetics; D007783:Lactones / Q000737:chemistry*; D008049:Lipase / Q000037:antagonists & inhibitors / Q000737:chemistry*; D013237:Stereoisomerism
D007783:Lactones; C420503:methylpropiothiolactone; D008049:Lipase