Adhesion ability of angiotensin II with model membranes

The octa-peptide angiotensin II (Ang II, (H2N-Asp–Arg–Val–Tyr–Ile–His–Pro–Phe–COOH)) 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 oneof several peptide ligands binding to G protein coupled receptors (GPCR). The activehormone derives from a high molecular weight precursor sequentially cleaved by theproteases renin and the angiotensin converting enzyme (ACE). The chemical natureof the amino acid sequence has an impact on the behavior in the proximity ofmembranes, demonstrated using different membrane model systems and biophysicalmethods.Applying electrochemical impedance spectroscopy and small angle x-ray scattering adetailed view on the adhesion of the peptide with model membrane surfaces wasperformed. The role of specific amino acids involved in the interaction with thephospholipid head group were investigated and, studying a truncated version of AngII, Ang (1-7), the key role of the C-terminal phenylalanine was proven. Truncation ofthe C-terminal amino acid abolishes the binding of the peptide to the membranesurface. A shift in pH, altering the protonation state of the central histidine residueimpairs the adhesion of Ang II