Molecular Dynamics Simulations of Cooling in Laser-Excited Heme Proteins
Abstract
In transient optical experiments the absorbed photon raises the vibrational temperature of the chromophore. In heme proteins at room temperature conversion of a 530-nm photon into vibrational energy is estimated to raise the temperature of the heme by 500-700 K. Cooling of the heme is expected to occur mainly by interacting with the surrounding protein. We report molecular dynamics simulations for myoglobin and cytochrome c in vacuo that predict that this cooling occurs on the ps time scale. The decay of the vibrational temperature is nonexponential with about 50% loss occurring in 1-4 ps and with the remainder in 20-40 ps. These results predict the presence of nonequilibrium vibrational populations that would introduce ambiguity into the interpretation of transient ps absorption and Raman spectra and influence the kinetics of sub-ns geminate recombination.
- Publication:
-
Proceedings of the National Academy of Science
- Pub Date:
- December 1986
- DOI:
- 10.1073/pnas.83.23.8982
- Bibcode:
- 1986PNAS...83.8982H