Figure 5. The ligand-acceptor binding interaction between amantadine and p7 channel at binding site Trp21.

(A) The docking structure between amantadine and p7 channel at the site Trp21. (B). QM calculation for cation-π interaction between CH₃NH₃ ⁺ and the aromatic side chain of Trp. The protonated amino group (−NH₃ ⁺) of amantadine perpendicularly points to the π-plane of Trp21, and forms a stable cation-π bond. The cation-π bond length is 2.99 Å and the interaction energy is −82.53 kJ/mol.