Charge Transfer Stabilization of Hemoglobin Structures

摘要

The porphyrin macrocycle in heme proteins is embedded in a hydrophobic pocket. Although it is clear that many functional properties of heme proteins are governed by the interaction between the heme and its local environment, the detailed nature of these forces has not been explored. We have recently developed a highly sensitive Raman difference spectroscopy to assess the importance of such forces by studying perturbations on the heme due to changes in this protein environment. Application of this technique to ferrous deoxyhemoglobins with quaternary structures stabilized by chemical modification of the proteins yields Raman frequency differences which correlate with conformational stabilization. Similarly, changes are observed in certain Raman modes when the allosteric effector, IHP, is added to methemoglobins. These data provide evidence for an electronic stabilization between the heme and the protein. (ERA citation 05:021250)