Stereochemistry of iron in deoxyhaemoglobin

The EXAFS of human deoxyhaemoglobin closely resembles that of a synthetic model in which the displacement of the iron from the mean porphyrin plane is 0.426 +/- 0.004 A, similar to the displacement of 0.56 +/- 0.03 A found by single crystal X-ray analysis of deoxyhaemoglobin. We find the same Fe-N of 2.06 +/- 0.01 A distance as Eisenberger et al., but show that the displacement of the iron from the nitrogen plane cannot be calculated from that distance.