Photoinactivation of Photosystem II at low light intensity
نویسندگان
چکیده
We studied the effect of low light intensity on Photosystem II (PSII) of thylakoid membranes isolated form spinach. The application of low frequency single turnover flashes results in the decreased oxygen evolving activity of PSII. This effect was explained in the framework of a model, which assumes that saturating visible light flashes at low frequency can result in the degradation of the D1 protein, since S2,3/QB and S2/QA recombinations generate singlet oxygen through the intermediate triplet chlorophyll formation. We propose a pathway for the light-induced transitions and dark period processes of the S-states, which results the best fit of our experimental data. Acta Biol Szeged 46(3-4):167-169 (2002)
منابع مشابه
Photoinactivation of Photosystem II in Prochlorococcus and Synechococcus
The marine picocyanobacteria Synechococcus and Prochlorococcus numerically dominate open ocean phytoplankton. Although evolutionarily related they are ecologically distinct, with different strategies to harvest, manage and exploit light. We grew representative strains of Synechococcus and Prochlorococcus and tracked their susceptibility to photoinactivation of Photosystem II under a range of li...
متن کاملPhotoinactivation of Catalase Occurs under Both High- and Low-Temperature Stress Conditions and Accompanies Photoinhibition of Photosystem II.
Severe photoinactivation of catalase (EC 1.11.1.6) and a decline of variable fluorescence (F(v)), indicating photoinhibition of photosynthesis, were observed as rapid and specific symptoms in leaves exposed to a high heat-shock temperature of 40 degrees C as well as in leaves exposed to low chilling temperatures in white light of only moderately high photosynthetic photon flux density of 520 mu...
متن کاملA Hard Day's Night: Diatoms Continue Recycling Photosystem II in the Dark
Marine diatoms are photosynthetic, and thrive in environments where light fluctuates. Like all oxygenic photosynthetic organisms diatoms face a light-dependent inactivation of the Photosystem II complexes that photooxidize water to generate biosynthetic reductant. To maintain photosynthesis this photoinactivation must be countered by slow and metabolically expensive protein turnover, which is l...
متن کاملBicarbonte stimulation, of oxygen evolution, ferricyanide reduction and photoinactivation using isolated chloroplasts
Dependence of Hill reaction (ferricyanide reduction) by isolated (broken) chloroplasts on bicarbonate ion increases with time of illumination (upto 4 min) in HCC>3~ free reaction mixture. The stimulation caused by HCOs" is independent of light intensity down to very low intensities indicating an involvement of this ion in early photochemical events of photosystem II. Oxygen evolution was found ...
متن کاملPhotosystem II photoinactivation, repair, and protection in marine centric diatoms.
Diatoms are important contributors to aquatic primary production, and can dominate phytoplankton communities under variable light regimes. We grew two marine diatoms, the small Thalassiosira pseudonana and the large Coscinodiscus radiatus, across a range of temperatures and treated them with a light challenge to understand their exploitation of variable light environments. In the smaller T. pse...
متن کامل