Uncouplers Stimulate Photosynthesis in Intact Chloroplasts by Enhancing Light-Activation of Enzymes Regulated by the Ferredoxin-Thioredoxin System
AUTOR(ES)
Rosa, Luciana
RESUMO
Some uncouplers stimulate CO2-dependent O2 evolution by intact spinach chloroplasts at pH 8.6. This effect is not due to alkalinization of the stroma. The stimulation is observed only when photosynthesis has been partly inhibited by the presence of H2O2, generated in a Mehler-type reaction by the broken chloroplasts which always contaminate the intact chloroplast preparations. The addition of methyl viologen increases the Mehler-type reaction and results in greater inhibition of photosynthesis. The addition of excess catalase stimulates photosynthesis by preventing accumulation of H2O2. The uncouplers stimulate photosynthesis primarily by enhancing the light-activation of enzymes that are regulated by the ferredoxin-thioredoxin system, and this effect results from the influence of the uncouplers on the redox poising of the ferredoxin in the intact chloroplasts.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=427492Documentos Relacionados
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