Fig. 6.

Location of the conserved Ala-404 residue in the active site of rabbit reticulocyte 15-LOX-1. In this detailed view from the crystal structure (29), iron (orange) in the center of the catalytic domain is held in place by conserved ligands (light blue). The sixth coordination position faces an open cavity, occupied here by a lipoxygenase inhibitor (green) and is presumably the location of fatty acid during catalysis. The conserved Ala-404 (blue) lies beyond the iron in a suitable position for influencing oxygenation of the activated substrate. On the far side of the protein, there is visible access into the active site over the polypeptide chain of Ala-404. Residues on the lower-right side include Ile-418 and Met-419 (red), shown earlier to influence binding of the ω chain of substrate AA (14). On the top left is Arg-403 (yellow), a residue exposed on the far side of the protein surface and suggested to interact with the carboxylic end of AA in this enzyme (32).