Comparison of key NA-ligand interactions.

All residues are N2 numbered and distances are given in Å. The 4-guanidino group of zanamivir, laninamivir and CS-8958 is abbreviated as ‘4-guan’. Bond distances are based on the distances between oxygen and nitrogen atoms and do not include hydrogen atoms, which cannot be directly observed using X-ray diffraction. Distances are given for molecule A in the asymmetric unit of each structure and are highly consistent between molecules. The distance of the unique hydrogen bond between the laninamivir octanoate 9-ester-O and p09N1 Asn294 is given for both molecules A and B as it varies significantly. Laninamivir octanoate is listed as CS-8958 to save space.*The Asp151 side chain carboxy hydrogen bonds with the 4-N of all the ligands used in this study.**The Asp151 and Trp178 backbone carbonyl groups both hydrogen bond with the 4-guanidino group of zanamivir, laninamivir and laninamivir octanoate.***The laninamivir octanoate 9-ester-carbonyl forms a hydrogen bond with N2 Arg224.