Light saturation curves and quantum yields in reaction centers from photosynthetic bacteria

Reaction centers isolated from the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26 mutant were irradiated with laser pulses of variable energy and the amount of photooxidation of the primary electron donor bacteriochlorophyll was measured. The resultant light saturation curve fits an expo...

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Bibliographic Details
Published in:Biophysical journal 1984-02, Vol.45 (2), p.455-461
Main Authors: Cho, H.M., Mancino, L.J., Blankenship, R.E.
Format: Article
Language:English
Subjects:
bacteriochlorophylls
Biological and medical sciences
Cell structures and functions
Chloroplast, photosynthetic membrane and photosynthesis
Fundamental and applied biological sciences. Psychology
Kinetics
Light
Molecular and cellular biology
photooxidation
Photosynthesis
Quantum Theory
reaction centers
Rhodobacter sphaeroides - metabolism
Rhodopseudomonas sphaeroides
Space life sciences
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Summary:Reaction centers isolated from the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26 mutant were irradiated with laser pulses of variable energy and the amount of photooxidation of the primary electron donor bacteriochlorophyll was measured. The resultant light saturation curve fits an exponential function and not a hyperbolic or hyperbolic tangent function. Analysis using either a Poisson statistical model or a simple kinetic model predicts an exponential light saturation curve in the limit where the light pulse is long relative to any transient intermediate states. The absolute quantum yield of photochemistry was found to be 0.98, utilizing the entire light saturation curve. Distortions from the simple exponential light saturation behavior are predicted when very short laser pulses are used.
ISSN:0006-3495
1542-0086
DOI:10.1016/S0006-3495(84)84168-5