Figure 1.

The cyclophilin glycine double mutant is pre‐organized for peptide binding. a)–c) Chemical shift changes (CSC) and details of [¹⁵N,¹H]‐Transverse relaxation optimized spectroscopy (TROSY) spectra are shown for protein bound to: a) cis‐peptide; b) trans‐peptide; and c) WT peptide (WT). d) The difference in CSC for WT cyclophilin and G74A and G75A bound to the respective ligands (CSC_{wild‐type/peptide}−CSC_{G74A/G75A/peptide}) is plotted as a function of amino acid residues. Arrows indicate the residues responsible for ligand binding. The cis‐peptide shows a clear trend not seen for the WT and trans‐ligand. e)–h) Spectral expansions are shown for the active site residues Cys52, Phe60, Ala101 and His126, for free and bound WT and mutant G74A and G75A. The top and bottom panel of each pair represent the WT protein and the G74A and G75A mutant, respectively, in free protein form (red), bound to cis‐peptide (cyan), trans‐peptide (green), and WT peptide (blue). All of the experiments were done with an 11‐fold excess of the peptide ligand (0.3 mm protein and 3.4 mm ligand). Residues in the vicinity of the active site residues are also labeled. Arrows indicate the chemical shift changes induced upon addition of ligand.