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. Author manuscript; available in PMC: 2009 Aug 14.
Published in final edited form as: Proteins. 2008 Nov 15;73(3):690–704. doi: 10.1002/prot.22097

Figure 2.

Figure 2

Distribution of histidine ligand orientation for different heme types. The relative frequency of different histidine ligand orientations (alpha) taken from the nonredundant heme protein data set overlaid over the heme plane. Angles are grouped in 10° bins. (A) b-type heme histidine ligands show a relatively even distribution with a maximal relative frequency of ≈9% at −170° (n = 68). (B) Ligands of c-type hemes that are not part of the CXXCH motif are distributed over the whole range with 17% near +80° (n = 42). (C) Ligands of c-type hemes ligands in the CXXCH motif show only two preferred orientations with ≈90% between +20° and −30 and ≈10% between +40° and +90° (n = 58).