title: 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.
authors.affiliation: Laboratory of Biophysics, Department of Experimental Physics, Faculty of Science, Palacký University, tr. 17. Listopadu 12, Olomouc, Czech Republic.
authors.forename: Deepak Kumar
authors.initials: DK
authors.lastname: Yadav
authors.forename: Jerzy
authors.initials: J
authors.lastname: Kruk
authors.forename: Rakesh Kumar
authors.initials: RK
authors.lastname: Sinha
authors.forename: Pavel
authors.initials: P
authors.lastname: Pospíšil
mesh_terms: D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers / Q000494:pharmacology*; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000378:metabolism; D010971:Plastoquinone / Q000031:analogs & derivatives* / Q000737:chemistry; D026082:Singlet Oxygen / Q000737:chemistry*; D019097:Spin Trapping; D018724:Spinacia oleracea / Q000737:chemistry*
chemical_list: D016166:Free Radical Scavengers; D045332:Photosystem II Protein Complex; D026082:Singlet Oxygen; C003165:plastoquinol; D010971:Plastoquinone