Browsing by Author "Talts, Eero"
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Item Photosynthetic cyclic electron transport : measurement and variably proton-coupled mechanism(Tartu University Press, 2010-02-15T07:58:58Z) Talts, EeroIn plant photosynthesis, linear electron transport (LET) from H2O to NADP+ and to CO2 further on is coupled with transmembrane H+ transport supporting ATP synthesis. The stoichiometry of 3ATP/2NADPH = 12H+/4e- is the absolute requirement for CO2 reduction. For a half of a century it has been a common belief that violations of this stoichiometry are corrected by cyclic electron transport (CET) during which some electrons are cycling around photosystem I (PSI) in an H+ coupled way. Though CET was detected in plant leaves, its rate was never exactly quantified, as well the amount of CET-related ATP synthesis was not compared with the actual ATP needs. In this work CET rate was measured and the assumed ATP synthesis quantified in leaves under experimental conditions where the metabolic ATP consumption was reduced to minimum. Differently from the present common belief, CET rate is at maximum when ATP is at maximum and its additional synthesis is unnecessary. The conclusion is that CET is variably coupled with transmembrane H+ translocation. Therefore the new model of CET is developed to explain this situation.Item Ribuloos-1,5-bifosfaadi karboksülaasi-oksügenaasi aktiivsus tubakas ja selle seos fotosüsteem I hulgaga(2005) Talts, Eero; Laisk, Agu, juhendaja