Movement of Fe with respect to the heme plane in the R-T transition of carp hemoglobin. An EXAFS study.

Carp Hb undergoes a well known change in kinetics over the pH range 6-9. X-ray absorption spectroscopy, in conjunction with refined data analysis procedures, shows no differences in iron-ligand distances when Carp HbCO is switched from R (high affinity) states. These distances are 2.015 +/-0.015Angstroms for the average iron-pyrrole - nitrogen distance, 2.14 +/-0. 04Angstroms for the iron-nitrogen (of histidine) distance, and 1.89+/-0.05Angstroms for the Fe-C(of CO) distance.