The rate of formation of P700+-A0- in photosystem I particles from spinach as measured by picosecond transient absorption spectroscopy

Michael R Wasielewski, J. M. Fenton, Govindjee

Research output: Contribution to journalArticle

65 Citations (Scopus)

Abstract

Photosystem I particles containing 30-40 chlorophyll a molecules per primary electron donor P700 were subjected to 1.5 ps low density laser flashes at 610 nm resulting in excitation of the antenna chlorophyll a molecules followed by energy transfer to P700 and subsequent oxidation of P700. Absorbance changes were monitored as a function of time with 1.5 ps time resolution. P700 bleaching (decrease in absorbance) occurred within the time resolution of the experiment. This is attributed to the formation of 1P700.* This observation was confirmed by monitoring the rise of a broad absorption band near 810 nm due to chlorophyll a excited singlet state formation. The appearance of the initial bleach at 700 nm was followed by a strong bleaching at 690 nm. The time constant for the appearance of the 690 nm bleach is 13.7±0.8 ps. In the near-infrared region of the spectrum, the 810 nm band (which formed upon the excitation of the photosystem I particles) diminished to about 60% of its original intensity with the same 13.7 ps time constant as the formation of the 690 nm band. The spectral changes are interpreted as due to the formation of the charge separated state P700+-A0-, where A0 is the primary electron acceptor chlorophyll a molecule.

Original languageEnglish
Pages (from-to)181-189
Number of pages9
JournalPhotosynthesis Research
Volume12
Issue number2
DOIs
Publication statusPublished - Jan 1987

Fingerprint

Photosystem I Protein Complex
Spinacia oleracea
photosystem I
Absorption spectroscopy
spinach
spectroscopy
Spectrum Analysis
chlorophyll
Bleaching
bleaching
absorbance
Molecules
electrons
Electrons
energy transfer
Excited states
antennae
Energy transfer
Energy Transfer
lasers

Keywords

  • charge separation
  • photosystem I
  • picosecond spectroscopy
  • primary electron acceptor A
  • primary electron donor P700
  • primary photochemistry

ASJC Scopus subject areas

  • Plant Science

Cite this

The rate of formation of P700+-A0- in photosystem I particles from spinach as measured by picosecond transient absorption spectroscopy. / Wasielewski, Michael R; Fenton, J. M.; Govindjee.

In: Photosynthesis Research, Vol. 12, No. 2, 01.1987, p. 181-189.

Research output: Contribution to journalArticle

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