Importance of excitation and trapping conditions in photosynthetic environment-assisted energy transport

J Phys Chem B. 2014 Sep 11;118(36):10588-94. doi: 10.1021/jp505179h. Epub 2014 Aug 29.

Abstract

It has been argued that excitonic energy transport in photosynthetic complexes is efficient because of a balance between coherent evolution and decoherence, a phenomenon called environment-assisted quantum transport (ENAQT). Studies of ENAQT have usually assumed that the excitation is initially localized on a particular chromophore, and that it is transferred to a reaction center through a similarly localized trap. However, these assumptions are not physically accurate. We show that more realistic models of excitation and trapping can lead to very different predictions about the importance of ENAQT. In particular, although ENAQT is a robust effect if one assumes a localized trap, its effect can be negligible if the trapping is more accurately modeled as Förster transfer to a reaction center. Our results call into question the suggested role of ENAQT in the photosynthetic process of green sulfur bacteria and highlight the subtleties associated with drawing lessons for designing biomimetic light-harvesting complexes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Bacterial Proteins / metabolism
  • Chlorobi / metabolism*
  • Energy Transfer
  • Fluorescence Resonance Energy Transfer
  • Light-Harvesting Protein Complexes / metabolism
  • Markov Chains
  • Models, Chemical
  • Photosynthesis / physiology*

Substances

  • Bacterial Proteins
  • FMO bacteriochlorophyll protein, Bacteria
  • Light-Harvesting Protein Complexes