1H‐NMR study of gramicidin A transmembrane ion channel

Abstract

The structure of[Val1]gramicidin A incorporated into sodium dodecyl-d25 sulphate micelles has been studied by two-dimensional proton NMR spectroscopy. Analysis of nuclear Overhauser effects, spin-spin couplings and solvent accessibility of NH groups show that the conformation of the Na+ complex of gramicidin A in detergent micelles, which in many ways mimic the phospholipid bilayer of biomembranes, is an N-terminal to N-terminal (head-to-head) dimer formed by two right-handed, single-stranded β6.3 helices with 6.3 residues per turn, differing from Urry's structure by handedness of the helices