On vibrational cooling upon photodissociation of carbonmonoxymyoglobin and its microscopic mechanism from the viewpoint of vibrational modes of heme

We report some results via molecular dynamics simulations for the photodissociation process of carbonmonoxymyoglobin in vacuo. The vibrational temperature of heme shows a biphasic decay (time constants, 0.84 ps (66%) and 18.7 ps (34%), are in good agreement with the experimental ones). The vibrational frequencies of the active center were obtained by time-resolved Fourier transform of velocity autocorrelation functions. Then, the vibrational modes of propionate groups of heme would couple with those of a water molecule. Since these groups are exposed to the water solvent, they should play an important role for the channel of fast energy transfer from the heme protein to the solvents.