Interaction between an amantadine analogue and the transmembrane portion of the influenza A M2 protein in liposomes probed by 1H NMR spectroscopy of the ligand.

1H NMR spectroscopy of a fluoroamantadine ligand was used to probe the pH dependence of binding to the transmembrane peptide fragment of the influenza A M2 proton channel (M2TM) incorporated into 1,2-dimyristoyl-sn-glycero-3-phosphocholine liposomes. Above pH 7.5, when M2TM bound the ligand, fluoroamantadine resonances became too broad to be detected. Fluoroamantadine interacted weakly with the liposomes, indicating it may first bind to the bilayer and then block target channels after diffusion across the membrane surface.