The Soret magnetic circular dichroism of ferric high-spin myoglobins. A probe for the distal histidine residue.

摘要: To find a simple criterion for the presence of distal (E7) histidine residue in myoglobins and hemoglobins, Soret magnetic-circular-dichroic spectra were examined ferric metmyoglobins from various species. A distinct symmetric dispersion-type curve was obtained containing histidine, whereas relatively weak unsymmetric pattern observed lacking this residue, such as those three kinds gastropodic sea molluscs, shark African elephant. The would thus be direct reflection or absence water molecule at sixth coordinate position heme iron(III), axial ligand being stabilized by hydrogen-bond formation to residue. On basis these signals, we also structure protozoan myoglobin (or monomeric hemoglobin) Paramecium caudatum particular interest evolution proteins protozoa higher animals.