Primary events in biology probed by ultrafast laser spectroscopy. Chapter 3. Electron transfer reactions in photosynthetic bacteria
Some features distinguish bacterial and plant photosynthetic processes. Bacteria use a single photosystem while plants use two photosystems. Also, because the bacteriochlorophyll (BChl) pigments of bacteria absorb longer wavelengths of light than the chlorophyll (Chl) pigments of plants, bacteria utilize a larger portion of the solar spectrum. However, both bacteria and plants use arrays of pigments as antennae to harvest the sun's energy. This harvested energy is transferred to sites called reaction centers (RCs). The elementary chemical reactions in RCs are electron transfers. The present understanding of RC electron transfer steps is described. Modeling work was performed to correlate electrochemical, spectroscopic, and geometric parameters to help predict the likelihood of electron transfer reactions. To summarize the modeling work, the cofacial diporphyrin models compare favorably with natural photosystems. The distances and rates of ET are similar, and both store >90% of the incident photons energy in ET products. These conclusions lend strong support to RC electron transfer schemes that employ an electron transfer intermediate between (BChl)/sub 2/ and BPheo. The modeling studies suggest that a close to cofacial arrangement may be necessary for rapid electron transfer even at donor to acceptor separations of <7A. (ERB)
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 6869060
- Report Number(s):
- BNL-28439
- Country of Publication:
- United States
- Language:
- English
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14 SOLAR ENERGY
ELECTRON TRANSFER
BIOCHEMICAL REACTION KINETICS
PHOTOSYNTHETIC BACTERIA
CHLOROPHYLL
EXPERIMENTAL DATA
LASER SPECTROSCOPY
MATHEMATICAL MODELS
PHOTOCHEMICAL REACTIONS
PIGMENTS
BACTERIA
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
KINETICS
MICROORGANISMS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYTOCHROMES
PORPHYRINS
REACTION KINETICS
SPECTROSCOPY
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