Flash-yield pattern for photosynthetic oxygen evolution in Chlorella and chloroplasts as a function of excitation intensity
1979
Jursinic, P.
A study was carried out of the changes in flash-yield pattern for oxygen evolution at various light intensities. Oxygen measurements were made on algal and chloroplast samples, using a Joliot-type polarographic electrode. A mathematical model to describe the behavior of oxygen-evolving systems at various flash intensities was developed based on the binomial distribution. This model is capable of accurately predicting the oxygen flash-yield pattern over two orders of magnitude change in light intensity. The observed oxygen flash yields are accounted for at all flash intensities without changing the probability for misses and double hits by oxygen-evolving systems. It is concluded that intrinsic misses and double hits are observed, which are nearly independent of flash intensity. Also, the apparent optical cross section for oxygen evolution is found to increase as flash intensity decreases. It is suggested that inhomogeneity exists in the size of antenna-pigment aggregates associated with photosystem II reaction centers.
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