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. Author manuscript; available in PMC: 2010 Oct 23.
Published in final edited form as: J Mol Biol. 2009 Aug 22;393(2):308–319. doi: 10.1016/j.jmb.2009.08.042

Figure 1.

Figure 1

Model and electron density revealing a metallated protoporphyrin IX bound within the active site of the A monomer for the wild-type human ferrochelatase enzyme treated with protoporphyrin IX and either Hg (Panel a) or Cd (Panel b). The model is shown in stick format and the 2Fo-Fc composite omit map (green cage) was generated using the simulated annealing protocol with 7% of the model omitted per cycle. The lower image in both panels is the same data shown in the top image rotated by 90°. Carbon, nitrogen, oxygen, and iron atoms are colored tan, blue, red, and orange respectively and the composite omit map is contoured at 1 σ.