CONFORMATIONAL RELAXATION AND LIGAND-BINDING TO SINGLY REDUCED HUMAN EMBRYONIC HEMOGLOBINS

The reaction of the three human embryonic haemoglobins with aquated el ectrons follows a complex set of steps in which a single haem centre u ndergoes both reduction and spin state changes coupled to slower prote in relaxation events. In the presence of ferrous haem ligands the spin state changes are coupled directly to the ligand binding process. The rate constants for the reaction of the single reduced haem with O-2 a re similar to those determined by flash photolysis at high pH, whilst CO binding to the beta type haems is more rapid and the alpha haems le ss rapid than the analogous processes observed using photolysis techni ques.