Photosynthesis Research

, Volume 92, Issue 1, pp 55–63

Two equilibration pools of chlorophylls in the Photosystem I core antenna of Chlamydomonas reinhardtii

  • Krzysztof Gibasiewicz
  • V. M. Ramesh
  • Su Lin
  • Kevin Redding
  • Neal W. Woodbury
  • Andrew N. Webber
Regular Paper

DOI: 10.1007/s11120-006-9125-1

Cite this article as:
Gibasiewicz, K., Ramesh, V.M., Lin, S. et al. Photosynth Res (2007) 92: 55. doi:10.1007/s11120-006-9125-1

Summary

Femtosecond transient absorption spectroscopy was applied for a comparative study of excitation decay in several different Photosystem I (PSI) core preparations from the green alga Chlamydomonas reinhardtii. For PSI cores with a fully interconnected network of chlorophylls, the excitation energy was equilibrated over a pool of chlorophylls absorbing at ∼683 nm, independent of excitation wavelength [Gibasiewicz et al. J Phys Chem B 105:11498–11506, 2001; J Phys Chem B 106:6322–6330, 2002]. In preparations with impaired connectivity between chlorophylls, we have found that the spectrum of chlorophylls connected to the reaction center (i.e., with ∼20 ps decay time) over which the excitation is equilibrated becomes excitation-wavelength-dependent. Excitation at 670 nm is finally equilibrated over chlorophylls absorbing at ∼675 nm, whereas excitation at 695 nm or 700 nm is equilibrated over chlorophylls absorbing at ∼683 nm. This indicates that in the vicinity of the reaction center there are two spectrally different and spatially separated pools of chlorophylls that are equally capable of effective excitation energy transfer to the reaction center. We propose that they are related to the two groups of central PSI core chlorophylls lying on the opposite sides of reaction center.

Keywords

AntennaChlorophyllsExcitation energy transferFemtosecond transient absorptionPhotosystem IPrimary charge separationReaction center

Abbreviations

A0

Primary acceptor

A1

Secondary quinone acceptor

Chl

Chlorophyll

DADS

Decay associated difference spectrum

ND

Non-decaying

P700

Primary donor

PB

Photobleaching

PSI

Photosystem I

RC

Reaction center

SE

Stimulated emission

Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • Krzysztof Gibasiewicz
    • 1
    • 3
    • 4
  • V. M. Ramesh
    • 1
    • 3
  • Su Lin
    • 2
    • 3
  • Kevin Redding
    • 5
  • Neal W. Woodbury
    • 2
    • 3
  • Andrew N. Webber
    • 1
    • 3
  1. 1.School of Life Sciences, Department of Chemistry and Biochemistry and Center for the Study of Early Events in PhotosynthesisArizona State UniversityTempeUSA
  2. 2.Department of Chemistry and BiochemistryArizona State UniversityTempeUSA
  3. 3.Center for the Study of Early Events in PhotosynthesisArizona State UniversityTempeUSA
  4. 4.Department of PhysicsAdam Mickiewicz UniversityPoznanPoland
  5. 5.Department of ChemistryUniversity of AlabamaTuscaloosaUSA