IR vibrational echo experiments are used to study dynamics in myoglobin (Mb) by investigating the dephasing of the CO-stretching mode of CO bound at the active site of the protein (Mb-CO). The temperature dependence and the viscosity dependence of Mb-CO pure dephasing have been measured in several solvents. In low-temperature, glassy solvents, the pure dephasing has a power law temperature dependence, 1.3, that reflects glasslike protein dynamics. In liquids, the temperature dependence is much steeper and arises from a combination of pure temperature dependence and the influence of decreasing solvent viscosity with increasing temperature. As the solvent viscosity decreases, the ability of the protein's surface to undergo topological fluctuations increases, which in turn increases the internal protein-structural fluctuations. The protein-structural motions are coupled to the CO bound at the active site by electric field fluctuations that accompany movements of polar residues. The dynamic electric field-coupling mechanism is tested by observing differences in the temperature dependence of the pure dephasing of Mb-CO mutations.


Article metrics loading...

Loading full text...

Full text loading...


Data & Media loading...

  • Article Type: Review Article
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error