Figure 3. Effect of various PQ-1 concentrations on EPR signal intensity of the EMPO-OOH adduct measured in spinach PSII membrane particles.

PSII membrane particles were illuminated with white light (900 μE·m⁻²·s⁻¹) for 5 min in the presence of 25 mM EMPO, 100 μM desferal, 150 μg of chl·ml⁻¹, 40 mM Mes (pH 6.5) and PQ-1 as indicated.