Figure 3.

Stereo view of the comparison of procollagenase-1 with the active enzyme. (a) Active human MMP-1 (pink), procollagenase-1 (green; PDB code: 1SU3) and prostromelysin-1 (grey; PDB code: 1SLM) have been superimposed to highlight the major movement of Phe81 (N-terminal residue of active enzyme; Phe83 in active stromelysin-1) upon activation. Also shown is the resulting salt-bridge between Phe81 and Asp232. The dotted green line represents the likely trajectory the N-terminal segment (81–87) would take in the procollagenase-1. The prostromelysin-1 structure was superimposed to help visualise this movement as this segment in the procollagenase-1 structure is disordered. (b) Close-up of the N-terminal area (the area boxed in (a). Colour coding for the structures is the same as that followed for (a).