Interaction of electron acceptors with thylakoids from halophytic and non-halophytic species |
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Authors: | Christopher Preston Christa Critchley |
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Affiliation: | (1) Botany Department, The Faculties, Australian National University, GPO Box 4, 2601 Canberra, ACT, Australia;(2) Present address: Photoconversion Research Branch, Solar Energy Research Institute, 1617 Cole Blvd., Golden, CO, USA;(3) Botany Department, University of Queensland, 4067 St Lucia, QLD, Australia |
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Abstract: | Thylakoid membranes isolated from halophytic species showed differences in their interactions with ionic and lipophilic electron acceptors when compared to thylakoids from non-halophytes. FeCN was considerably less efficient as electron acceptor with halophyte thylakoids, supporting much lower rates of O2 evolution and having a lower affinity. FeCN accepted electrons at a different, DMMIB insensitive, site with these thylakoids. 1,4-Benzo-quinones with less positive midpoint potentials were less effective in accepting electrons from halophyte thylakoids compared to nonhalophyte thylakoids, also reflected in lower rates of O2 evolution and lower affinity. Considering the lipolphilic nature and the fact that there was no apparent change in the site donating electrons to the quinones, an alteration in the midpoint potential of this site by about +100mV is postulated for the halophyte thylakoids.Abbreviations AMPD 2-amino-2-methyl-1,3-propanediol - Cyt b6/f cytochrome b6/f complex - DBMIB 2,5-dibromo-6-isopropyl-3-methyl-1,4-benzoquinone - DCBQ 2,6-dichloro-1,4-benzoquinone - DCIP 2,6-dichlorophenol-indolphenol - DMBQ 2,5-dimethyl-1,4-benzoquinone - Em7 midpoint redox potential at pH 7.0, FeCN-K3Fe(CN)6 - HNQ 5-hydroxy-1,4-naphthoquinone - MV methylviologen - NQ 1,4-naphthoquinone - PBQ phenyl-1,4-benzoquinone - PC plastocyanin - PQ plastoquinone |
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Keywords: | electron transport halophyte mangrove photosystem II spinach thylakoid |
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