Mechanisms for excited state relaxation and dissociation of oxymyoglobin and carboxymyoglobin.
The dissociation of carboxymyoglobin (MbCO) and oxymyoglobin (MbO2) induced by 530-nm picosecond excitation in the beta band or the 355-nm delta band has been measured by monitoring the absorbance changes at 420 and 440 nm corresponding to ligand-bound and ligand-detached species, respectively. We find that MbO2 and MbCO dissociate with very similar rates, which do not reflect the 30-fold difference between the quantum yields of the two reactions. Kinetic data suggest that a short-lived intermediate is formed that is responsible for the low quantum efficiency of the MbO2 dissociation.
D000818:Animals; D007700:Kinetics; D008027:Light; D009211:Myoglobin / Q000528:radiation effects; D010100:Oxygen; D011485:Protein Binding; D013057:Spectrum Analysis; D014907:Whales
D009211:Myoglobin; D010100:Oxygen