This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.105.072652v1 90/8/2890    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Novoderezhkin, V. I. Articles by van Grondelle, R. Search for Related Content PubMed PubMed Citation Articles by Novoderezhkin, V. I. Articles by van Grondelle, R.

Dynamics of the Emission Spectrum of a Single LH2 Complex: Interplay of Slow and Fast Nuclear Motions

Vladimir I. Novoderezhkin ^*, Danielis Rutkauskas  and Rienk van Grondelle 

^* A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia; and Department of Biophysics and Physics of Complex Systems, Division of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, 1081 HV Amsterdam, The Netherlands

Correspondence: Address reprint requests to Danielis Rutkauskas, Fax: 31-20-5987999; E-mail: danielis{at}nat.vu.nl.

We have studied the relationship between the realizations of static disorder and the emission spectra observed for a single LH2 complex. We show that the experimentally observed spectral fluctuations reflect realizations of the disorder in the B850 ring associated with different degrees of exciton delocalization and different effective coupling of the excitons to phonon modes. The main spectral features cannot be explained using models with correlated disorder associated with elliptical deformations of the ring. A quantitative explanation of the measured single-molecule spectra is obtained using the modified Redfield theory and a model of the B850 ring with uncorrelated disorder of the site energies. The positions and spectral shapes of the main exciton components in this model are determined by the disorder-induced shift of exciton eigenvalues in combination with phonon-induced effects (i.e., reorganization shift and broadening, that increase in proportion to the inverse delocalization length of the exciton state). Being dependent on the realization of the disorder, these factors produce different forms of the emission profile. In addition, the different degree of delocalization and effective couplings to phonons determines a different type of excitation dynamics for each of these realizations. We demonstrate that experimentally observed quasistable conformational states are characterized by excitation energy transfer regimes varying from a coherent wavelike motion of a delocalized exciton (with a 100-fs pass over half of the ring) to a hopping-type motion of the wavepacket (with a 350-fs jump between separated groups of 3–4 molecules) and self-trapped excitations that do not move from their localization site.

This article has been cited by other articles:

				D. Abramavicius, D. V. Voronine, and S. Mukamel Double-quantum resonances and exciton-scattering in coherent 2D spectroscopy of photosynthetic complexes PNAS, June 24, 2008; 105(25): 8525 - 8530. [Abstract] [Full Text] [PDF]

				R. Croce, A. Chojnicka, T. Morosinotto, J. A. Ihalainen, F. van Mourik, J. P. Dekker, R. Bassi, and R. van Grondelle The Low-Energy Forms of Photosystem I Light-Harvesting Complexes: Spectroscopic Properties and Pigment-Pigment Interaction Characteristics Biophys. J., October 1, 2007; 93(7): 2418 - 2428. [Abstract] [Full Text] [PDF]

				V. I. Novoderezhkin, J. P. Dekker, and R. van Grondelle Mixing of Exciton and Charge-Transfer States in Photosystem II Reaction Centers: Modeling of Stark Spectra with Modified Redfield Theory Biophys. J., August 15, 2007; 93(4): 1293 - 1311. [Abstract] [Full Text] [PDF]