Determination of the primary charge separation rate in isolated photosystem II reaction centers with 500-fs time resolution

Journal Article · Sun Jan 01 00:00:00 EST 1989 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.86.2.524· OSTI ID:5104148

Wasielewski, M R; Johnson, D G ^[1]; Seibert, M ^[2]; Govindjee, ^[3]

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1. Argonne National Laboratory, IL (USA)
2. Solar Energy Research Institute, Golden, CO (USA)
3. Univ. of Illinois, Urbana (USA)

The authors have measured directly the rate of formation of the oxidized chlorophyll a electron donor (P680+) and the reduced electron acceptor pheophytin a{sup {minus}} (Pheoa{sup {minus}}) following excitation of isolated spinach photosystem II reaction centers at 4{degree}C. The reaction-center complex consists of D{sub 1}, D{sub 2}, and cytochrome b-559 proteins and was prepared by a procedure that stabilizes the protein complex. Transient absorption difference spectra were measured from 440 to 850 nm as a function of time with 500-fs resolution following 610-nm laser excitation. The formation of P680+-Pheoa{sup {minus}} is indicated by the appearance of a band due to P680+ at 820 nm and corresponding absorbance changes at 505 and 540 nm due to formation of Pheoa{sup {minus}}. The appearance of the 820-nm band is monoexponential with {tau} = 3.0 {plus minus} 0.6 ps. Treatment of the photosystem II reaction centers with sodium dithionite and methyl viologen followed by exposure to laser excitation, conditions known to result in accumulation of Pheoa{sup {minus}}, results in formation of a transient absorption spectrum due to {sup 1*}P680. They find no evidence for an electron acceptor that precedes the formation of Pheoa{sup {minus}}.

• DOE Contract Number: W-31-109-ENG-38
• OSTI ID: 5104148
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Vol. 86:2; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
PHOTOSYNTHETIC REACTION CENTERS
ABSORPTION SPECTRA
BIOCHEMICAL REACTION KINETICS
CHLOROPHYLL
ELECTRON TRANSFER
OXIDATION
PHOTOSYNTHESIS
SPINACH
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
FOOD
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
KINETICS
MAGNOLIOPHYTA
MAGNOLIOPSIDA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHYTOCHROMES
PIGMENTS
PLANTS
PORPHYRINS
PROTEINS
REACTION KINETICS
SPECTRA
SYNTHESIS
VEGETABLES
140505* - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)