Immobilization and interfacial activation of lipase at liquid and solid interfaces.

Abstract

This study investigates the adsorption behaviour of Candida rugosa lipase at silica/water and oil/water interfaces by means of molecular dynamics simulations. The findings reveal distinct adsorption orientations and structural differences that can be related to different enzymatic activities and selectivities. At the silica/water interface, lipase adsorbs with the LID region facing the solvent, in a configuration that is not fully open, but still grants access to its catalytic triad, as shown by tunnel calculations. These also reveal the presence of two ester-exit tunnels, suggesting a high catalytic turnover capability of the adsorbed enzyme. Docking simulations predict binding of triacylglyceride substrates with marked selectivity regarding the length of the hydrophobic chains and the substrate chirality. At the oil/water interface, lipase adsorbs via the LID region with widely open ingress tunnels, facilitating direct substrate extraction from the interface. The two opposite adsorption orientations allow favorable interactions of silica-immobilized lipase with oil droplets that cause no appreciable change in the conformation, activity, or selectivity. These results provide a molecular-scale rationalization of the lipid hydrolysis mechanisms that support the deployment of lipase immobilized in ceramic membranes for lipolytic applications.