Singlet oxygen scavenging activity of plastoquinol in photosystem II of higher plants: Electron paramagnetic resonance spin-trapping study

Abstract

Singlet oxygen (1O2) scavenging activity of plastoquinol in photosystem II (PSII) of higher plants was studied by electron paramagnetic resonance (EPR) spin-trapping technique. It is demonstrated here that illumination of spinach PSII membranes deprived of intrinsic plastoquinone results in 1O2 formation, as monitored by TEMPONE EPR signal. Interestingly, the addition of exogenous plastoquinol (PQH2-1) to PQ-depleted PSII membranes significantly suppressed TEMPONE EPR signal. The presence of exogenous plastoquinols with a different side-chain length (PQH2-n, n isoprenoid units in the side chain) caused a similar extent of 1O2 scavenging activity. These observations reveal that plastoquinol exogenously added to PQ-depleted PSII membranes serves as efficient scavenger of 1O2. © 2010 Elsevier B.V.