Diffusion and Catalysis Processes in Unilamellar Liposomes

Abstract

This research concerns the study of enzyme loaded unilamellar vesicles as bioreactors. The plant enzyme Ascorbic Acid Oxidase (AAO) was entrapped in unilamellar liposomes.

Kinetic study shows that the enzyme activity is largely criptic and that the enzyme in liposomes is partially protected against proteolysis. In order to describe the reactivity of such a system, a kinetic model was developed which accounts both for the enzyme location and for the substrate diffusion across the lipid membrane. For the building of the kinetic model we have used information derived from previous studies of freeze-fracture and label fracture microscopy, which have shown that the protein is located both inside the aqueous core and across the lipid membrane of the vesicles.