Combined Electrochemistry and Surface-Enhanced Infrared Absorption Spectroscopy of Gramicidin A Incorporated into Tethered Bilayer Lipid Membranes

摘要

Membrane proteins exert a variety of fundamental functions such as electron and proton transfer, voltage-gated ion translocation, and enzymatic transformations. Since most of these processes can be monitored and controlled by electrochemical techniques, substantial efforts have been made to develop strategies for immobilizing membrane proteins on electrodes while preserving their native functions. In one of the most interesting approaches tethered membranes are used to immobilize functional integral proteins on an electrode surface. One strategy is to first attach a solubilized protein through a His tag to an appropriately functionalized metal surface, and then reconstitute a lipid bilayer around the fixed protein by detergent-lipid exchange. In these protein-tethered lipid bilayers, however, protein mobility is severely restricted and the overall stability of the device is limited, in particular on non-ideal surfaces. Another more promising and versatile approach is.based on lipid-tethered bilayer lipid membranes (tBLMs), which consist of a self-assembled monolayer (SAM) of amphiphiles covalently attached to a metal electrode and a lipid layer on top of the SAM formed from fused unilamellar vesicles. This approach can be used to insert integral membrane proteins into the tBLM (Figure 1). These devices closely mimic the natural environment of membrane-bound proteins, both with respect to the architecture and the excellent electrical properties, and display very good long-term stability.