Photosystem photo inhibition

Mishra NP, Mishra RK and Singhal GS (1993) Involvement of active oxygen species in photoinhibition of Photosystem II protection of photosynthetic efficiency and inhibition of lipid peroxidation by superoxide dismutase and catalase. J Photo-chem Photobiol B Biol 19 19-24 Miyake C and Asada K (1992) Thylakoid-bound ascorbate peroxidase in spinach chloroplasts and photoreduction of its primary oxidation product monodehydroascorbate radicals in thylakoids. Plant Cell Physiol 33 541-553 Miyake C and Asada K (1994) Ferredoxin-dependent photoreduction of the monodehydroascorbate radical in spinach thylakoids. Plant Cell Physiol 35 539-549 Miyake C, Schreiber U, Hermann H, Sano S and Asada K (1996) Monodehydroascorbate radical reductase-dependent photoreduction of oxygen in chloroplast thylakoids. Plant Cell Physiol 37 s284... 

Photoinhibition (1) occurs when oxygenic photosynthetic organisms or isolated photo- synthetic membranes are exposed to strong illumination. It results in impaired electron tran- sport and decreased CO2 assimilation and is caused by inhibition of reactions in photosystem II. 

DCMU, hydroxylamlne or 0-phenanthrollne, both photo-oxidation and photoreduction were abolished. Similarly, since photo-oxidative consumption of ascorbate was inhibited by 0-phenan-throllne, Chiba and Okayama (1962) also proposed the role of AA as an electron donor for photosystem II. Phosphorylation and peroxide formation during ascorbate photo-oxidation in the presence of low redox potential was observed by others CForti and Jagendorf, 1961 Trebst et al., 1963 Jacobi, 1964) who suggested that AA reacts with the electron transfer system at a site related to the O2 evolution system. 

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