Lipase activity on immobilized vesicles

With the help of a quartz crystal microbalance with built-in dissipation monitoring, we have studied the hydrolytic mechanism of the lipase lecitase towards intact vesicles and immobilized bilayers. QCM-D can clearly follow breakdown of vesicles and removal of SPBs, though direct binding of enzyme, tested using non-hydrolyzable ether lipids, lies below the detection threshold. The data can be fitted very well to a Voight-based model describing the change in film thickness and viscosity with time. Initial enzyme binding to intact vesicles is accompanied by significant changes in vesicle structure prior to vesicle rupture. This phenomenon is sensitive to vesicle charge, suggesting it is due to the accumulation of hydrolysis products in the vesicle which affect its viscoelastic properties (Pernille H. Justesen, Tina Kristensen, Daniel Otzen).