Figure 3. NMR characterization of the amantadine binding site.

a, Representative strips from the 3D ¹⁵N-edited NOESY-TROSY spectrum (300 ms NOE mixing time) recorded using a sample containing ¹⁵N-, ²H-labeled p7(5a) and 10 mM amantadine, showing amantadine NOEs to the backbone amide protons of Val26, Leu55, Leu56, and Arg57. b, Representative strips from the 3D diagonal-suppressed ¹³C-edited NOESY-HSQC spectrum recorded using a sample that is ¹H-, ¹³C-labeled at the methyl positions of alanines, valines and leucines but is otherwise deuterated, showing drug NOEs to the sidechain methyl protons of Val26, Leu52, and Val53. The spectra in a and b were recorded at ¹H frequency of 900 MHz. c, Amantadine docked into the p7(5a) hexamer using restraints from NOEs in a and b (left) and a close view of amantadine in the binding pocket (right).