Figure 1.

Principal component analysis (PCA) of substrate-free CypA and substrate-bound CypA complexes. The top three principal components’ dominant motions are shown, with each data point representing a conformation of the active site residues. Depicted are the substrate-free enzyme (black), the trans-CypA complex (red), the transition-state-CypA complex (green), the cis-CypA complex (blue), and the substrate-bound CypA complex with hydrophobic active-site residues (on white surface). Also depicted are the active site residues (Arg⁵⁵, Gln⁶³, and Asn¹⁰²) and Trp¹²¹ that form hydrogen bonds with the substrate (sticks), and the substrate in the transition state configuration (yellow).