Primary events in biology probed by ultrafast laser spectroscopy. Chapter 3. Electron transfer reactions in photosynthetic bacteria

Technical Report · Tue Jan 01 04:00:00 EST 1980

OSTI ID:6869060

Netzel, T L

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

Related Subjects

14 SOLAR ENERGY
140505 -- Solar Energy Conversion-- Photochemical
Photobiological
&amp; Thermochemical Conversion-- (1980-)
550200* -- Biochemistry
550700 -- Microbiology
59 BASIC BIOLOGICAL SCIENCES
BACTERIA
BIOCHEMICAL REACTION KINETICS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHLOROPHYLL
DATA
ELECTRON TRANSFER
EXPERIMENTAL DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
KINETICS
LASER SPECTROSCOPY
MATHEMATICAL MODELS
MICROORGANISMS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHETIC BACTERIA
PHYTOCHROMES
PIGMENTS
PORPHYRINS
REACTION KINETICS
SPECTROSCOPY