Figure 3. Driving force for the opening of the N2 150-loop.

(a) Hydrogen bond occupancy related to the 150-loop in the five simulation systems. Grey: FREE-H150-Neu; green: ZMR-H150-Pos; yellow: OST-NH3-H150-Pos; pink: OST-NH2-H150-Pos; red: OST-NH2-H150-Neu. (b) The opening process of the 150-loop in OST-NH2-H150-Neu trajectory (Chain D) represents the similar conformational change to the crystal structure. Upper panel: 150-cavity volume; down: the distance between alpha carbon of D151 and nitrogen atom of Oseltamivir carboxylate amino group (black), the nearest distance between OD1 or OD2 of D147 and ND1 of H150 (green), and the nearest distance between OD1 or OD2 of D147 and NE atom of R107 in the neighboring molecule (red). (c) Comparison of the interactions between N2 residues and amino group of oseltamivir carboxylate and guanidino group of zanamivir (within 3 Å).