Pig-liver esterase, which catalyzed the hydrolysis of substrates containing both saturated and α, β-unsaturated/cyclopropanecarboxylic esters (methyl and ethyl), was studied. An exclusive hydrolysis of the saturated esters was observed. Kinetic experiments revealed that the presence of deactivated carbonyl in the unsaturated/cyclopropanecarboxylic esters and their weaker bindings are both responsible for the observed specificity. The relative ...