Fig. 1.

NOESY crosspeaks between the active site Trp 90 H^Nε1 and nearby methyl groups in FKBP51 (A) and FKBP52 (B). The homologous position in FKBP12 is indicated in parentheses. The F2-F3 plane at the indole ¹H^Nε1 frequency from a 3D F1-filtered ¹H-¹³C-¹H NOESY spectrum of collected using a 200 ms mix time (black) is superimposed upon the reference 2D ¹H,¹³C HSQC spectrum containing all selectively enriched valine C^γ, leucine C^δ and isoleucine C^δ positions (green). The observable crosspeaks from the 3D NOESY spectrum have intensities that are consistent with the canonical orientation of the indole ring.