Figure 3. The ligand-acceptor binding interaction between amantadine and p7 ion channel at binding site His17.

(A) The docking structure between amantadine and p7 channel at the site His17. (B). QM calculation for cation-π interaction between CH₃NH₃ ⁺ and the aromatic side chain of His. The protonated amino group (−NH₃ ⁺) of amantadine perpendicularly points to the π-plane of His17, and forms a stable cation-π bond. The cation-π bond length is 3.072 Å and the interaction energy is −50.28 kJ/mol.