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EPR measurements on the effects of bicarbonate and triazine resistance on the acceptor side of Photosystem II
Author(s) -
Vermaas Wim F.J.,
Rutherford A.William
Publication year - 1984
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(84)80744-9
Subject(s) - photosystem ii , electron paramagnetic resonance , thylakoid , chemistry , p680 , pheophytin , crystallography , biophysics , photochemistry , photosystem i , photosynthesis , biochemistry , biology , chloroplast , nuclear magnetic resonance , gene , physics
CO 2 depletion leads to an approximately 10‐fold increase in the light‐induced EPR signal at g = 1.82, attributed to the Q A − · Fe 2+ complex, in Photosystem II‐enriched thylakoid membrane fragments. Upon reconstitution with HCO 3 − the signal decreases to the size in control samples. The split pheophytin − signal is broader in control or reconstituted than in CO 2 ‐depleted samples. It is concluded that HCO 2 − strongly influences the localization and conformation of the Q A − · Fe + complex. The Q A − · Fe 2+ and split pheophytirr − EPR signals from triazine‐resistant Brassica napus were virtually identical to those from triazine‐susceptible samples, indicating that the change in the 32‐kDa azidoatrazine‐binding protein does not lead to a confonnational change of the Q a − · Fe 2+ complex.