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Participation of the g = 1.9 and g = 1.82 EPR forms of the semiquinone‐iron complex, Q A − ·Fe 2+ of photosystem II in the generation of the Q and C thermoluminescence bands, respectively
Author(s) -
Demeter S.,
Goussias Ch.,
Bernát G.,
Kovács L.,
Petrouleas V.
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)80836-j
Subject(s) - semiquinone , electron paramagnetic resonance , chemistry , recombination , thermoluminescence , photosystem ii , dcmu , analytical chemistry (journal) , photochemistry , atomic physics , nuclear magnetic resonance , luminescence , physics , optics , biochemistry , photosynthesis , chromatography , gene
Following illumination at 200 K, the charge recombination reactions and the origin of the thermoluminescence (TL) bands appearing at about 0°C (Q band) and +50°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°C and +25°C, respectively, suggest that the S 2 state (multi‐line signal) undergoes charge recombination with the g = 1.9 form of the semiquinone‐iron complex, Q A − ·Fe 2+ , resulting in the appearance of the Q band, and that the g = 1.82 form of Q A − ·Fe 2+ back‐reacts with the oxidized tyrosine, Y D + (Signal II s ), accounting for the generation of the C band.