Heterocyclic ortho-quinones, a novel type of Photosystem II inhibitors.
Members of the new chemical class of 7-substituted 6-bromo-benzo[4,5]imidazo[1,2alpha]pyridin-8,9-diones were found to be excellent inhibitors at the Q(B) site of the photosystem II D1 reaction center protein. The best inhibitors with pI(50)-values of >7 are: dimethyl-propyl, 7.05; i-pentyl, 7.36; t. butyl, 7.47; and i-propyl, 7.51. Displacement experiments with [14C]atrazine revealed that the 8,9-diones behave non-competitively in respect of Photosystem II herbicides and, hence, have to be considered as a new type of Photosystem II inhibitors. This notion is further corroborated by their inhibitory activity in D1 mutants of Chlamydomonas reinhardtii.
Lehstuhl Biochemie der Pflanzen, Ruhruniversität, Bochum, Germany.
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Oettmeier
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Masson
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Hecht
D000818:Animals; D001280:Atrazine / Q000494:pharmacology; D016825:Chlamydomonas reinhardtii; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism; D006540:Herbicides / Q000494:pharmacology; D015394:Molecular Structure; D045322:Photosynthetic Reaction Center Complex Proteins / Q000037:antagonists & inhibitors*; D045332:Photosystem II Protein Complex; D010971:Plastoquinone / Q000737:chemistry; D011809:Quinones / Q000138:chemical synthesis / Q000494:pharmacology*; D018724:Spinacia oleracea; D014961:X-Ray Diffraction
D006540:Herbicides; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D011809:Quinones; D010971:Plastoquinone; D001280:Atrazine