title: Participation of the g = 1.9 and g = 1.82 EPR forms of the semiquinone-iron complex, QA-.Fe2+ of photosystem II in the generation of the Q and C thermoluminescence bands, respectively.
abstract: Following illumination at 200 K, the charge recombination reactions and the origin of the thermoluminescence (TL) bands appearing at about 0 degree C (Q band) and +50 degrees C (C band) in the glow curve were investigated by comparative TL and EPR measurements in DCMU-treated photosystem II particles. Decay half-time measurements carried out at -25 degrees C and +25 degrees C, respectively, suggest that the S2 state (multi-line signal) undergoes charge recombination with the g = 1.9 form of the semiquinone-iron complex, QA-.Fe2+, resulting in the appearance of the Q band, and that the g = 1.82 form of QA-.Fe2+ back-reacts with the oxidized tyrosine, YD+ (Signal IIs), accounting for the generation of the C band.
authors.affiliation: Institute of Plant Biology, Biological Research Center, Hungarian Academy of Sciences, Szeged.
authors.forename: S
authors.initials: S
authors.lastname: Demeter
authors.forename: C
authors.initials: C
authors.lastname: Goussias
authors.forename: G
authors.initials: G
authors.lastname: Bernát
authors.forename: L
authors.initials: L
authors.lastname: Kovács
authors.forename: V
authors.initials: V
authors.lastname: Petrouleas
mesh_terms: D016227:Benzoquinones / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D006358:Hot Temperature; D007501:Iron / Q000737:chemistry*; D008027:Light; D049449:Luminescence; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D045332:Photosystem II Protein Complex
chemical_list: D016227:Benzoquinones; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; C025232:semiquinone radicals; D007501:Iron