title: Inhibition of electron flow and energy transduction in isolated spinach chloroplasts by the herbicide dinoseb.
abstract: The mode of action of dinoseb (2-sec-butyl-4-6-dinitrophenol) on chloroplast reactions was studied. Electron flow from water or from an artificial electron donor, diphenylcarbazide (DPC), to dichlorophenol indophenol (DCPIP) was inhibited at low concentrations of the herbicide (5--10 microM) suggesting a site for dinoseb inhibition at the oxidizing side of photosystem II (PS II). Ferricyanide photoreduction was also inhibited by dinoseb. Cyclic and non-cyclic photophosphorylation and Mg2+-ATPase activity were inhibited by dinoseb, which indicates that this herbicide also acts as an energy transfer inhibitor. Among the above mentioned activities, non-cyclic photophosphorylation was the most sensitive to the inhibition by dinoseb. Ca2+-ATPase activity of solubilized heat activated chloroplast coupling factor 1 (CF1) was stimulated by dinoseb. However, the same activity was inhibited in chloroplasts, which perhaps reflect a difference in the mode of interaction of dinoseb with solubilized and membrane bound coupling factor.
mesh_terms: D019297:2,4-Dinitrophenol / Q000031:analogs & derivatives*; D002736:Chloroplasts / Q000187:drug effects* / Q000378:metabolism; D004140:Dinitrophenols / Q000494:pharmacology*; D004583:Electrons; D004735:Energy Transfer / Q000187:drug effects; D006540:Herbicides / Q000494:pharmacology*; D010788:Photosynthesis / Q000187:drug effects*; D014675:Vegetables
chemical_list: D004140:Dinitrophenols; D006540:Herbicides; D019297:2,4-Dinitrophenol; C018527:dinoseb