Vectorial insertion of bacteriorhodopsin for directed orientation assays in various polymeric biomembranes

Abstract

Here we demonstrate the rapid reconstitution and preserved functionality of vectorially-inserted bacteriorhodopsin from Halobacterium Halobium in ABA block copolymer thin films. We have utilized a triblock copolymeric membrane that simulates biological systems as a matrix to enable protein refolding to observe the activity of bacteriorhodopsin in purple membrane form as well as in individual molecules. In addition to observing protein–polymer compatibility properties using polymers of varying lengths (4 vs. 8.4 nm in height) and compositions (UV-cross-linkable methacrylate or acrylate ended), we have observed that vectorial insertion of the proteins, and hence, the directionality of proton pumping is dependent upon the pH of the medium to manipulate the asymmetric charge density of the polymer membrane during reconstitution.