Fig. 1

N-terminal lobe binding site of lactoferrin (PDB 1b0l) showing the iron (red sphere) coordinated with CO₃ ²⁻ (red triskelion) and the surrounding amino acids from the cleft domains (yellow and green). The hinge is found in the region between yellow and green colored structural elements in the upper left. The width of the cleft can be characterized by the C_α-distance between Asp60 and Tyr192 with 11.3 Å (broken line), which becomes 19.3 Å in the open configuration. Arg121 is located at the helix 5 N-termini