The formation and substrate specificity of bacterial lactonases capable of enantioselective resolution of racemic lactones

The substrate specificities of epsilon-caprolactone hydrolase from Acinetobacter NCIMB 9871 and delta-valerolactone hydrolase from Pseudomonas NCIMB 9872 were investigated. Both lactonases showed activity toward six- and seven-membered ring lactones. delta-Valerolactone hydrolase exhibited enantioselectivity in its activity. It showed a preference for the R enantiomer of delta-decanolactone and delta-nonalactone whereas epsilon-caprolactone hydrolase showed little enantioselectivity toward the lactone substrates tested The delta-valerolactone hydrolase front Pseudomonas NCIMB 9872 may be useful for the resolution of racemic lactones, and hence may serve as an alternative route to chiral lactone synthesis.