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Femtosecond spectroscopy of electron transfer in the reaction center of the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26: direct electron transfer from the dimeric bacteriochlorophyll primary donor to the bacteriopheophytin acceptor

Journal Article · · Proc. Natl. Acad. Sci. U.S.A.; (United States)
; ; ; ;
The primary light-induced charge separation in reaction centers from Rhodopseudomonas sphaeroides R-26 has been investigated after excitation with laser pulses of 150 fsec duration within the longwave absorption band of the primary donor at 850 nm. An excited state of the primary donor, characterized by a broad absorption spectrum extending over the whole spectral range investigated (545-1240 nm), appeared within 100 fsec and gave rise to stimulated emission in the 870- to 1000-nm region with a 2.8-psec lifetime. The photooxidation of the primary donor, as measured at 1240 nm, and the photoreduction of the bacteriopheophytin acceptor, monitored at 545 nm and 675 nm, have been found to proceed simultaneously with a time constant of 2.8 +/- 0.2 psec. Kinetics of absorbance changes at other probe wavelengths gave no indication that an accessory bacteriochlorophyll is involved as a transient electron acceptor.
Research Organization:
Ecole Polytechnique, Palaiseau, France
OSTI ID:
6443886
Journal Information:
Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 83:4; ISSN PNASA
Country of Publication:
United States
Language:
English

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Related Subjects

14 SOLAR ENERGY
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
ABSORPTION SPECTRA
BACTERIA
BIOCHEMICAL REACTION KINETICS
CARBOXYLIC ACIDS
CHLOROPHYLL
ELECTRON TRANSFER
ENERGY-LEVEL TRANSITIONS
EXCITATION
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
KINETICS
LASER SPECTROSCOPY
MICROORGANISMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOSYNTHETIC REACTION CENTERS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
PROTEINS
REACTION KINETICS
RHODOPSEUDOMONAS
SPECTRA
SPECTROSCOPY