Modulation of electron transfer kinetics by protein conformational fluctuations during early-stage photosynthesis.
The kinetics of electron transfer during the early stages of the photosynthetic reaction cycle has recently been shown in transient absorption experiments carried out by Wang et al. [Science 316, 747 (2007)] to be strongly influenced by fluctuations in the conformation of the surrounding protein. A model of electron transfer rates in polar solvents developed by Sumi and Marcus using a reaction-diffusion formalism [J. Chem. Phys. 84, 4894 (1986)] was found to be successful in fitting the experimental absorption curves over a roughly 200 ps time interval. The fits were achieved using an empirically determined time-dependent function that described protein conformational relaxation. In the present paper, a microscopic model of this function is suggested, and it is shown that the function can be identified with the dynamic autocorrelation function of intersegment distance fluctuations that occur in a harmonic potential of mean force under the action of fractional Gaussian noise.
Chaudhury
Srabanti
S
Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India.
Cherayil
Binny J
BJ
D000042:Absorption; D004058:Diffusion; D004579:Electron Transport; D007700:Kinetics; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000378:metabolism; D011336:Probability; D011487:Protein Conformation; D012997:Solvents / Q000737:chemistry
D045322:Photosynthetic Reaction Center Complex Proteins; D012997:Solvents