Mouth loop arrangements of KshA5. Comparison of the mouth loop in KshA5 (A), KshA5·ADD (B), and KshA5·1,4-BNC-CoA (C). Mouth loop residues are colored cyan, and substrate is colored green. Substrate (C atoms in green), Tyr-226 (cyan), and Thr-260 and Phe-300 (white) are represented as sticks, and the iron ion is an orange sphere. Figure was generated using PyMOL (50).