Temperature Dependence of the Energy Transfer in LHCII Studied by Two-Dimensional Electronic Spectroscopy

J Phys Chem B. 2019 Aug 8;123(31):6765-6775. doi: 10.1021/acs.jpcb.9b05421. Epub 2019 Jul 30.

Abstract

We measured two-dimensional electronic spectra of light-harvesting complex II (LHCII) at various temperatures (77, 110, 150, 230, and 295 K) under conditions free from singlet-singlet annihilation. We elucidated the temperature-dependent excitation energy transfer dynamics in the Chl a manifold of LHCII. Global analysis revealed that the dynamics can be summarized in distinct time scales from 200 fs up to 15 ps. While the fastest dynamics with a decay time of ∼0.2-0.3 ps are relatively temperature-independent, the lifetimes and relative contributions of slower components showed considerable temperature dependence. The slowest time scale of equilibration with the lowest-energy Chl a increased from ∼5 ps at 295 K to ∼15 ps at 77 K. The final excited state is independent of initial excitation at 230 K and above, whereas static energy disorder is apparent at lower temperatures. A clear temperature dependence of uphill energy transfer processes was also discerned, which is consistent with the detailed-balance condition.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chlorophyll A / chemistry
  • Chlorophyll A / radiation effects
  • Cold Temperature*
  • Energy Transfer*
  • Kinetics
  • Light
  • Light-Harvesting Protein Complexes / chemistry*
  • Light-Harvesting Protein Complexes / radiation effects
  • Pisum sativum / chemistry
  • Spectrum Analysis / methods

Substances

  • Light-Harvesting Protein Complexes
  • Chlorophyll A