Long-Range Effects in Liganded Hemoglobin Investigated by Neutron and UV Raman Scattering, FTIR, and CD Spectroscopies
文摘
The numerous investigations that have focused on theiron binding site to explain the different affinity ofhemoglobin for CO and O2 are still without success.Thus, this work addresses the problem of nonlocaleffects,which have been disregarded so far. We have investigated theprotein behavior in relation to the iron-ligand nature.The present data show that different parts of the protein, whichare not in close contact with the heme pocket, areeffectively influenced by the nature of the iron-ligand bond.Whereas oxyhemoglobin and carbonmonoxidehemoglobin in solution exhibit the same molecular shapes and helicalcontents, different electrostatic interactions inassociation with a redistribution of the strains occur in the proteinmatrix. Due to electric couplings of the heme tothe protein, the whole molecule is sensitive to the chemical nature ofthe iron-ligand bond. This suggests that longdistance electrostatic interactions promote the energy transductionthrough the protein molecule.