Figure 1.

Stereoview of briefly minimized NMR structures of NtrC^r. A) Side view of I-NtrC^r, B) side view of ${\text{BeF}}_3^{-}-{\text{NtrC}}^r$, C) top view of I-NtrC^r, D) top view of ${\text{BeF}}_3^{-}-{\text{NtrC}}^r$. The key helix, α4, is shown in black. Locations of residues Thr-82 (blue), Leu-87, Val-91, Tyr-94, Phe-99 (cyan), Tyr-101 (purple), Asp-54 (red), and His-84 (green) is indicated in top two figures. Residues Asp-10, Asp-11, Asp-12 are shown in yellow.