Stoichiometry of proton uptake in isolated pea chloroplasts under different light intensities

Иванов, Б. Н.; Shmeleva, V. L.; Ovchinnikova, V. I.

doi:10.1007/bf00744206

Cited by 6 publications

(1 citation statement)

References 31 publications

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“…There is the question of how the intrathylakoid proton concentration is controlled in vivo, and which electron transport reactions contribute to it. During transport of one electron from water to NADP (and from there to CO 2 ), the protonuelectron ratio is 3 (Hope et al, 1985;Ivanov et al, 1985;Rich, 1991;. CO 2 is reduced to the sugar level by 4 electrons.…”

Section: Introductionmentioning

confidence: 99%

Protection of the photosynthetic apparatus against damage by excessive illumination in homoiohydric leaves and poikilohydric mosses and lichens

Heber

Bukhov²,

Шувалов³

et al. 2001

Journal of Experimental Botany

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Experimental work on the control of photosystem II in the photosynthetic apparatus of higher plants, mosses and lichens is reviewed on a background of current literature. Transmembrane proton transport during photoassimilatory and photorespiratory electron flows is considered insufficient for producing the intrathylakoid acidification necessary for control of photosystem II activity under excessive illumination. Oxygen reduction during the Mehler reaction is slow. Together with associated reactions (the water-water cycle), it poises the electron transport chain for coupled cyclic electron transport rather than acting as an efficient electron sink. Coupled electron transport not accompanied by ATP consumption in associated reactions provides the additional thylakoid acidification needed for the binding of zeaxanthin to a chlorophyll-containing thylakoid protein. This results in the formation of energy-dissipating traps in the antennae of photosystem II. Competition for energy capture decreases the activity of photosystem II. In hydrated mosses and lichens, but not in leaves of higher plants, protein protonation and zeaxanthin availability are fully sufficient for effective energy dissipation even when photosystem II reaction centres are open. In leaves, an additional light reaction is required, and energy dissipation occurs not only in the antennae but also in reaction centres. Loss of chlorophyll fluorescence during the drying of predarkened poikilohydric mosses and lichens indicates energy dissipation in the dry state which is unrelated to protonation and zeaxanthin availability. Excitation of photosystem II by sunlight is not destructive in these dry organisms, whereas photosystem II activity of dried leaves is rapidly lost under strong illumination.

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Section: Introductionmentioning

confidence: 99%