Fig 5. Singlet oxygen detection in PSII membranes deprived of Mn₄O₅Ca complex using EPR spectroscopy.

TEMPONE EPR spectra [A, C] and a bar graph showing relative intensities of TEMPONE EPR signal [B, D]. PSII membranes deprived of Mn₄O₅Ca complex (200 μg Chl) were exposed to high light (1000 μmol photons m^-2 s^-1) in presence of 50 mM TMPD and 40 mM MES buffer (pH 6.5) for 30 min. In some experiments, 500 μM DPC or 50 μM desferal were added to the sample before illumination. For high pH effect, PSII membranes deprived of Mn₄O₅Ca complex were exposed to high light in buffers of different pH (40 mM HEPES buffer pH 7.5, 40 mM HEPES buffer 8.5 and40 mM CAPSO buffer pH 9.5). Data represent mean ± SD of three experiments.