Activity of Candida rugosa lipase for synthesis of hexyl octoate under high hydrostatic pressure and the mechanism of this reaction

Abstract

Candida rugosa lipase (CRL) in organic solvent was treated under high hydrostatic pressure. The lipase was activated at pressure below 300MPa while deactivated at pressure over 400MPa. Especially, the esterification activity of CRL was enhanced by 90% at 300MPa but reduced to 85% at 500MPa. Consistent with the activation of CRL under 300MPa, the ester yield and initial reaction rate was also enhanced significantly at this pressure incubated for 45min. In addition, the activation volume at moderate pressure (0.1–300MPa) was −6.46±1.2mL/mol at 40°C. The effects of substrate molar ratio and concentration suggested that the excess of the acid and alcohol both inhibited the lipase. The study of kinetics indicated that the mechanism of CRL-catalyzed hexyl octoate in isooctane followed a Ping-Pong Bi-Bi mechanism with dead-end inhibition by both substrates.