Adhesion ability of angiotensin II with model membranes.

The octa-peptide angiotensin II (Ang II, (HNAspArgValTyrIleHisProPheCOOH)) is one of the key player on blood pressure regulation in mammals. Predominantly binding to the Angiotensin type 1 and 2 receptors, the hormone is one of several peptide ligands binding to G protein coupled receptors (GPCR). The active hormone derives from a high molecular weight precursor sequentially cleaved by the proteases renin and the angiotensin converting enzyme (ACE).

Smart polymer brush nanostructures guide the self-assembly of pore-spanning lipid bilayers with integrated membrane proteins.

Nanopores in arrays on silicon chips are functionalized with pH-responsive poly(methacrylic acid) (PMAA) brushes and used as supports for pore-spanning lipid bilayers with integrated membrane proteins. Robust platforms are created by the covalent grafting of polymer brushes using surface-initiated atom transfer radical polymerization (ATRP), resulting in sensor chips that can be successfully reused over several assays. His-tagged proteins are selectively and reversibly bound to the nitrilotriacetic acid (NTA) functionalization of the PMAA brush, and consequently lipid bilayer membranes are formed.

Free-standing lipid films stabilized by Annexin-A5.

Free-standing lipid bilayers in nano- and micro-pores are interesting membrane models and attractive for biotechnological applications. We describe here the controlled preparation of proteo-lipid mono- and bilayers using the Langmuir-Schaefer transfer or Langmuir-Blodgett technique, respectively on hydrophobic and hydrophilic surfaces. We demonstrate the formation of suspended proteo-lipid layers by Transmission Electron Microscopy (TEM) and in situ Atomic Force Microscopy (AFM) imaging.

Techniques for recording reconstituted ion channels.

This review describes and discusses techniques useful for monitoring the activity of protein ion channels in vitro. In the first section the biological importance and the classification of ion channels are outlined in order to justify the strong motivation for dealing with this important class of membrane proteins. The expression, reconstitution and integration of recombinant proteins into lipid bilayers are crucial steps to obtain consistent data when working with ion channels.

Integration and recording of a reconstituted voltage-gated sodium channel in planar lipid bilayers.

Functional assays for membrane proteins become increasingly important in biosciences. We demonstrate the integration of reconstituted bacterial voltage-gated sodium channels (NaChBac) into preformed free-standing lipid bilayers by using the nystatin-ergosterol method to promote proteoliposome fusion. Vesicle delivery and subsequent NaChBac activity were monitored, the orientation of the transferred ion channels was assessed measuring at both, positive and negative holding potentials and the channel specificity was demonstrated by adding the blocker nimodipine.