Figure 3.

Serine protease domain. (A) Molecular surface of the Hap_S serine protease domain reveals a V-shaped binding groove (indicated by dashed line). The active site loop_265−275 (coloured in grey) is modelled based on the equivalent loop in the Hbp structure through structural superimposition. (B) Simulated complex of SLPI (cyan) bound to the Hap_S serine protease domain (red). The upper part of the helical spine and the protruding subdomains that mediate the orientation of the Hap_S serine protease domain are shown in cartoon diagram and coloured in grey and green, respectively. (C) Active site. Left panel: the serine protease domain is shown in electrostatic surface, and SLPI is shown in ribbon diagram (cyan). Right panel: close-up view of the active site. Simulated SLPI and surrounding residue from Hap_S are shown in stick and coloured in green and grey, respectively.