AVS 46th International Symposium
    Biomaterial Interfaces Group Monday Sessions
       Session BI-MoM

Paper BI-MoM9
Investigations into Peptide-tethered Lipid Bilayer Membranes

Monday, October 25, 1999, 11:00 am, Room 613/614

Session: Biosensor-Biology Interface
Presenter: L.C.R. Naumann, Max-Planck Institute for Polymer Research, Germany
Authors: L.C.R. Naumann, Max-Planck Institute for Polymer Research, Germany
E.K. Schmidt, Institute of Physical and Chemical Research (RIKEN), Japan
A. Offenhäusser, Max-Planck Institute for Polymer Research, Germany
W. Knoll, Max-Planck Institute for Polymer Research, Germany
Correspondent: Click to Email
Lipid-functionalised thiopeptides were employed to form peptide-tethered lipid monolayers on gold substrates. Upon fusion of liposomes these monolayers formed tethered lipid bilayer membranes (tBLM’s) well designed to incorporate membrane proteins such as H+-ATPase, Na,K-ATPase, cytochrome c oxidase (COX) and the acetylcholine receptor (AChR). Pure peptide-tBLMs and those mixed with a lateral spacer such as thioethanol were investigated with regard to protein incorporation which was followed by surface plasmon resonance spectroscopy (SPS). Electrical properties were assessed simultaneously by impedance spectroscopy (IS). Fluorescence microscopy showed the bilayers to be homogeneous, however, by FRAP measurements fluidity of the membranes was not observed. Fluorescence microscopy was also used to determine the surface concentration of fluorescein labeled COX. Binding assays were performed by SPS of agonists and antagonists of the receptors such as cyochrome c and bungarotoxin. The specificity and sensitivity of the binding assays was increased for primary monoclonal and secondary polyclonal antibodies against COX and the AChR by using an extension of SPS, surface plasmon enhanced fluorescence spectroscopy (SPFS). Proton transport through H+-ATPase from chloroplasts was then investigated with either coupled or non-coupled proton discharge at the gold electrode, depending on the applied potential. In cases where faradaic processes were involved, electrochemical techniques were applied, such as square wave voltammetry and chronoamperometry, where as proton transport across the lipid film was followed by IS. Impedance spectra thus showed characteristic changes as a function of adenosin-triphosphate (ATP) and inhibitor (venturicidin) concentration and/or bias potentials.