Figure 1

The crystal structure of alkaline protease from Pseudomonas aeruginosa (1KAP) to 1.64 Å and the β-roll domain in isolation. A) Full structure of the zinc metalloprotease [7] showing the zinc atom coordinated in the active site (blue sphere) and the calcium binding β-roll circled in black; B) Enlarged view looking down the axis of the β-roll of alkaline protease including the five bound calcium ions (orange spheres), the parallel β-strands and tight turns around the metal-binding sites and the side chains of the seven residues making contact with Ca²⁺ ions: Asp338, Asn347, Asp356, Asp365, Asp374, Asp 390 and Asp400; C) Enlarged view of the front face of the β-roll of alkaline protease with the same residues highlighted as in panel B.