CO vibration as a probe of ligand dissociation and transfer in myoglobin.
We report femtosecond visible pump, midinfrared probe, spectrally integrated experiments resolving the dynamics of CO in myoglobin upon photodissociation. Our results show a progressive change in absorption strength of the CO vibrational transition during its transfer from the heme to the docking site, whereas the vibrational frequency change is faster than our time resolution. A phenomenological model gives good qualitative agreement with our data for a time constant of 400 fs for the change in oscillator strength. Density-functional calculations demonstrate that indeed vibrational frequency and absorption strength are not linearly coupled and that the absorption strength varies in a slower manner due to charge transfer from the heme iron to CO.
Laboratoire d'Optique et Biosciences, UMR CNRS 7645, INSERM U451, Ecole Polytechnique, ENSTA, F-91128 Palaiseau, France.
T
T
Polack
J P
JP
Ogilvie
S
S
Franzen
M H
MH
Vos
M
M
Joffre
J-L
JL
Martin
A
A
Alexandrou
D055592:Biophysical Phenomena; D001703:Biophysics; D002248:Carbon Monoxide / Q000737:chemistry* / Q000378:metabolism*; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D008024:Ligands; D008956:Models, Chemical; D009211:Myoglobin / Q000737:chemistry* / Q000378:metabolism*; D010777:Photochemistry; D014732:Vibration
D008024:Ligands; D009211:Myoglobin; D006418:Heme; D002248:Carbon Monoxide