Relation between the mode of binding of nitrite and the energy distribution between the two photosystems

Autor: Archna Sahay, Anjana Jajoo, Sudhakar Bharti, Pooja Singh
Rok vydání: 2006
Předmět:
Zdroj: Physiologia Plantarum. 129:447-454
ISSN: 1399-3054
0031-9317
DOI: 10.1111/j.1399-3054.2006.00808.x
Popis: The reversibility of nitrite-induced inhibition in relation to energy distribution between the two photosystems was studied in spinach thylakoid membranes. Measurements of electron transfer rate catalyzed by photosystem I (PS I) and photosystem II (PS II), chlorophyll a (Chl a) fluorescence induction kinetics, s 2 state multiline spectra, and room temperature electron paramagnetic resonance (EPR) signals indicated that nitrite anions bind PS II in two ways: dissociable (loose) and non-dissociable (tight). The inhibition caused by the dissociable binding was reversible in washed (nitrite-treated samples washed with nitrite-free medium) samples, while the inhibition caused by the non-dissociable binding was irreversible. At 77 K, an increase in absorption cross section of PS I (as inferred from the excitation spectra of Chl a a fluorescence) and a decrease in absorption cross section of PS II in nitrite-treated sample when compared with sample washed with nitrite-free medium and control sample suggested that nitrite plays a role in regulating the distribution of absorbed excitation energy between the two photosystems. We propose, for the first time, that the removal of loosely bound nitrite leads to migration of light-harvesting complex II back to the PS II, and thus the mode of binding of nitrite regulates the extent of migration of antenna molecules between the two photosystems.
Databáze: OpenAIRE
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