Activity of trypsin-lipid complexes at oil/water interfaces

Abstract

Adsorption of trypsin at lipid-stabilized oil/water interfaces has been studied as a function of the nature of the interface. The adsorption of the enzyme, with corresponding changes in the activity expressed, is found to be related to the charge and nature of the lipid polar groups at the interface and to the charge and nature of the polar groups of the protein. Interactions between enzyme and lipid at the interface are paralleled in bulk with soluble lipid homologs. The loss in activity of the enzyme at the interfaces studied is thought to be due to a general structural unfolding of the molecule. Provided that the unfolding process has not gone too far, desorption of the surface enzyme can lead to partial recovery of activity. Some of the problems involved in the study of the effect of changes in the general structure of the protein on the enzymatic activity by the present methods are discussed. It is concluded that a determination of whether or not these partially “denatured” enzymes can work at lower efficiency necessitates careful investigation of the kinetic and thermodynamic properties of the adsorbed, partially unfolded enzyme.