Kinetics of enzymatic synthesis of isopropylidene glycerol esters by goat pregastric lipase

The goat pregastric lipase-catalyzed esterification of isopropylidene glyce rol with caproic acid, to form isopropylidene glycerol caproate, followed a ping pong bi bi mechanism incorporating an acyl-enzyme intermediate. The m aximum rate was estimated to be 96 mu mol min(-1) mg(-1) in isooctane at 35 degrees C, and the Michaelis-Menten constants for isopropylidene glycerol and caproic acid were 0.23 and 0.32 M, respectively. The catalyzed rate als o correlated well with the partition coefficient of caproic acid between th e organic and aqueous phases. The results suggest that the desolvation ener gy of the substrate from the bulk medium to the active site of the enzyme d ominates the reaction rate for the enzyme-catalyzed reaction in organic med ia.