Influence of globin structure on the heme in dromedary carbonmonoxyhemoglobin.

By use of X-ray absorption near-edge structure (XANES), circular dichroism, and visible absorption spectroscopies, dromedary carbonmonoxyhemoglobin has been characterized structurally and functionally. By consideration of the experimental results the following view emerges: (i) the quaternary structure is not the unique factor determining the tertiary environment around the heme, and (ii) the multiplicity of interactions between hemoglobin and solvent components induces a large number of globin conformations, which somehow affect the conformation of the heme such that the structural parameters (i.e., the doming of porphyrins, the movements of the iron relative to the heme plane, the distortion of the ligand field, and the change in the Fe-C-O angle) can be uncoupled.