Interaction of 2-n-heptyl-4-hydroxyquinoline-N-oxide with photosystem II in chloroplasts and subchloroplast particles [Herbicide, Pisum sativum, Amaranthus retroflexus]

• Published in: Journal of bioenergetics and biomembranes Vol. 15; no. 2; p. 93
• Main Authors: Barton, J.R, MacPeek, W.A, Cohen, W.S
• Format: Journal Article
• Language: English
• Published: United States 01.04.1983
• Subjects: Amaranthus - drug effects; Amaranthus - metabolism; Atrazine - pharmacology; Chloroplasts - drug effects; Chloroplasts - metabolism; Diuron - pharmacology; Electron Transport - drug effects; Ferricyanides - pharmacology; Herbicides - metabolism; Herbicides - pharmacology; Hydroxyquinolines - metabolism; Hydroxyquinolines - pharmacology; Photosystem II Protein Complex - drug effects; Photosystem II Protein Complex - metabolism; Picolines - pharmacology; Pisum sativum - drug effects; Pisum sativum - metabolism; Thylakoids - drug effects; Thylakoids - metabolism; Triazines - metabolism; Triazines - pharmacology
• ISSN: 0145-479X; 1573-6881
• DOI: 10.1007/BF00743222

The effects of 2-n-heptyl-4-hydroxyquinoline-N-oxide on electron transport in thylakoids and oxygen-evolving photosystem II particles has been examined. Kinetic fluorescence studies reveal that the site of inhibition for alkyl derivatives of hydroxyquinoline-N-oxide (I50 approximately equal to 2 microM) is located between Q and plastoquinone. Studies with thylakoids isolated from atrazine-resistant pigweed plants indicate that the modification in the Q/B membrane complex that confers increased resistance to inhibition by atrazine also results in decreased sensitivity to inhibition by 2-n-heptyl-4-hydroxyquinoline-N-oxide (resistant/ sensitive ratio = 11). From the results of tetramethylphenylenediamine by-pass experiments, determinations of inhibitor sensitivity in trypsin-treated thylakoids and competitive displacement experiments made with [14C]metribuzin in thylakoids and photosystem II particles, it is suggested that 2-n-heptyl-4-hydroxyquinoline-N-oxide binds in a region of the Q/B complex that is distinct from the 3-(3,4-dichloro)-1,1-dimethyl urea and atrazine binding sites.