(Structure and function in photosynthetic membranes and their components). Annual progress report, December 1, 1978-November 30, 1979
Structure and function are being studied in photosynthetic membranes and their components, principally with Rhodopseudomonas sphaeroides. That bacteriochlorophyll (Bchl) can have a strongly shifted absorption maximum in the membrane, without the involvement of excitonic Bchl-Bchl interactions was demonstrated. The orientations of pigments in the membrane are being determined, and the orientations of four distinguishable carotenoid components are under investigation. These studies provide data for computations of energy transfer and electron tunneling, and may bear on the mechanism of the electrogenic shifts of the absorption bands of carotenoids. New complexities in the absorption spectra of cytochromes were discovered, and new data concerning the distribution of carotenoids between antenna and reaction centers (RCs) in the membrane, and possible differences in their isomeric configuration were obtained. Antenna pigment-protein complexes and mutant phenotypes obtained elsewhere have been characterized. A corrected interpretation of the action of orthophenanthroline as an inhibitor of electron transport was presented. Analyses of RCs from Rp. viridis raised the possibility that the bound cytochromes Cyt 552 and Cyt 558 might consist of hemes attached to the RC protein. In collaboration with researchers at Harvard, an unusual temperature dependence for photoconversion of allophycocyanin isolated from cyanobacteria (blue-green algae) was found that has led to a stringent test of whether the photoconvertible allophycocyanin mediates chromatic adaptation in these organisms. Some theoretical studies of the problems that may arise in constructing solar cells from natural or artificial RCs have been conducted. (ERB)
- Research Organization:
- Cornell Univ., Ithaca, NY (United States)
- DOE Contract Number:
- EY-76-S-02-3162
- OSTI ID:
- 5266780
- Report Number(s):
- COO-3162-51
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CELL MEMBRANES
PHOTOCHEMICAL REACTIONS
CHLOROPHYLL
STRUCTURAL CHEMICAL ANALYSIS
CYTOCHROMES
ABSORPTION SPECTRA
BIOCHEMICAL REACTION KINETICS
PHOTOSYNTHETIC BACTERIA
PHOTOCHEMISTRY
CAROTENOIDS
ELECTRON TRANSFER
ORIENTATION
BACTERIA
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMICAL REACTIONS
CHEMISTRY
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
KINETICS
MEMBRANES
MICROORGANISMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
REACTION KINETICS
SPECTRA
TERPENES
550200* - Biochemistry
550700 - Microbiology
400500 - Photochemistry