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ENERGY TRANSFER BETWEEN PHOTOSYNTHETIC UNITS ANALYZED BY FLASH OXYGEN YIELD vs. FLASH INTENSITY *
Author(s) -
WANG RICHARD T.,
MYERS JACK
Publication year - 1973
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1973.tb06360.x
Subject(s) - flash (photography) , yield (engineering) , chlorella pyrenoidosa , transfer (computing) , trap (plumbing) , intensity (physics) , chemistry , photosynthesis , unit (ring theory) , atomic physics , analytical chemistry (journal) , materials science , physics , mathematics , optics , thermodynamics , chlorella , computer science , meteorology , botany , chromatography , biochemistry , biology , parallel computing , algae , mathematics education
— Relative yield of O 2 ( Y ) was measured in Chlorella pyrenoidosa in response to varied intensity ( l ) of single 10μsec flashes on a constant low background of 710 nm light. Analysis is based on the proposition that the photochemical event leading to O 2 evolution occurs at a reaction center or trap which requires a time much longer than the flash for regeneration by dark reactions. Hence O 2 , flash yield measures the number of traps ‘killed’ and allows treatment in terms of target theory. Data for Y vs. l were analyzed by computer fitting to four models. The first three models supposed that each unit (aggregate of light‐harvesting pigment molecules) contains one, two, and three traps, respectively, and allows no transfer of excitation energy out of the unit. The last model supposed only one trap per unit and a probability of transfer out of a unit with closed trap. Among the first three models, the data best fit the one with two traps per unit. A slightly better fit for two traps per unit was obtained by introducing a trapping efficiency less than unity. An equally good fit was also obtained with the model of the Joliots with a probability of 0.3 that excitation energy in a unit with closed trap is transferred to another unit. Uncertainties in analysis arose from the necessity of treating maximum flash yield as an estimated parameter and by the possible inhomogeneity in units and traps.