Bacteriochlorophyll protein structure - studies with polarized light and triplet state electron paramagnetic resonance
Light harverting bacteriochlorophyll-protein complexes from Rhodopseudomonas sphaeroides 2.4.1 (B800 + 850) and R-26 (LH-R26) mutant are solubiliized in SDS and imbedded in polyvinyl alcohol. Stretching induces orientation, and the linear dichroism of visible and near infrared absorption is analyzed. Based on a simple model, angles between the particle axis system and the transition dipole moments are found. Reaction centers of the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26, give rise to large triplet state EPR signals upon illumination at low temperature (11 K). Utilizing monochromatic polarized light to generate the EPR spectra (magnetophotoselection), it is shown that the intensities of the observed triplet signals are strongly dependent upon the wavelength and polarization direction of the excitation. Triplet states of carotenoids have been detected by EPR and are reported here for the first time. The systems in which carotenoid triplets are observed include cells of photosynthetic bacteria, isolated bacteriochlorophyll-protein complexes, and detergent micelles which contain ..beta..-carotene. The carotenoid triplet state is detected in reaction centers of Rhodopseudomonas sphaeroides 2.4.1 (wild type), which contain the carotenoid spheroidene.
- Research Organization:
- California Univ., Berkeley (USA). Lawrence Berkeley Lab.
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5645588
- Report Number(s):
- LBL-10560
- Resource Relation:
- Other Information: Thesis
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHLOROPHYLL
MOLECULAR STRUCTURE
RHODOPSEUDOMONAS
ELECTRON SPIN RESONANCE
TRIPLETS
BACTERIA
CARBOXYLIC ACIDS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
MAGNETIC RESONANCE
MICROORGANISMS
MULTIPLETS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
RESONANCE
550200* - Biochemistry
550700 - Microbiology