Spectroscopic characterization of the excitation energy transfer in the fucoxanthin-chlorophyll protein of diatoms

Photosynth Res. 2005 Nov;86(1-2):241-50. doi: 10.1007/s11120-005-1003-8.

Abstract

We characterized the energy transfer pathways in the fucoxanthin-chlorophyll protein (FCP) complex of the diatom Cyclotella meneghiniana by conducting ultrafast transient absorption measurements. This light harvesting antenna has a distinct pigment composition and binds chlorophyll a (Chl-a), fucoxanthin and chlorophyll c (Chl-c) molecules in a 4:4:1 ratio. We find that upon excitation of fucoxanthin to its S2 state, a significant amount of excitation energy is transferred rapidly to Chl-a. The ensuing dynamics illustrate the presence of a complex energy transfer network that also involves energy transfer from the unrelaxed or 'hot' intermediates. Chl-c to Chl-a energy transfer occurs on a timescale of a 100 fs. We observe no significant spectral evolution in the Chl-a region of the spectrum. We have applied global and target analysis to model the measured excited state dynamics and estimate the spectra of the states involved; the energy transfer network is discussed in relation to the pigment organization of the FCP complex.

MeSH terms

  • Algal Proteins / chemistry*
  • Algal Proteins / metabolism
  • Chlorophyll*
  • Diatoms / chemistry*
  • Energy Transfer
  • Kinetics
  • Light-Harvesting Protein Complexes / chemistry*
  • Light-Harvesting Protein Complexes / metabolism
  • Spectrum Analysis
  • Temperature
  • Xanthophylls*

Substances

  • Algal Proteins
  • Light-Harvesting Protein Complexes
  • Xanthophylls
  • fucoxanthin-, chlorophyll a-c-containing protein
  • fucoxanthin
  • Chlorophyll