The effect of herbicides on components of the PS II reaction centre measured by EPR

FEBS Letters

Zimmermann, J.L.¹  Rutherford, A.W.¹  Mathis, P.¹ 

[1]Service de Biophysique, Département de Biologie, Centre d'Etudes Nucléaires de Saclay, 91191 Gif-sur-Yvette Cedex, France

关键词: Herbicide;    Photosystem II;    Plastoquinone;    Pheophytin;    ADRY reagent;    Cytochrome b 559;    EPR;    Photosynthesis;    Adry;    reagents which accelerate the deactivation reactions of the water splitting enzyme;    DCMU;    3-(3;    4-dichlorophenyl)-1;    1-dimethylurea;    dinoseb;    2;    4-dinitro-6-s-butylphenol;    Hepes;    N-2-hydroxyethylpiperazine-N-2-ethanesulphonic acid;    Mes;    2-(N-morpholino)ethanesulphonic acid;    o-phen o-phenanthroline;   

DOI  :  10.1016/0014-5793(84)80161-1

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Incubation of PS II membranes with herbicides results in changes in EPR signals arising from reaction centre components. Dinoseb, a phenolic herbicide which binds to the reaction centre polypeptide, changes the width and form of the EPR signal arising from photoreduced Q⁻ _AFe. o-Phenanthroline slightly broadens the Q⁻ _AFe signal. These effects are attributed to changes in the interaction between the semi-quinone and the iron. DCMU, which binds to the 32 kDa protein, has virtually no effect on the width of the Q⁻ _AFe signal but does give rise to an increase in its amplitude. This could result from a change in redox state of an interacting component. Herbicide effects can also be seen when Q⁻ _AFe is chemically reduced and these seen to be reflected by changes in splitting and amplitude of the split pheophytin⁻ signal. Dinoseb also results in the loss of ‘Signal II dark’, the conversion of reduced high-potential cytochrome b ₅₅₉ to its oxidized low-potential form and the presence of transiently photooxidized carotenoid after a flash at 25°C; these effects indicate that dinoseb may also act as an ADRY reagent.

【 授权许可】

Unknown