Herbicide-Binding Protein, Binding Sites and Electron-Transport Activity: Quantitative Relations

ln Bumilleriopsis filiformis, the thylakoid-membrane protein showing the highest turnover in the light has an apparent molecular weight o f 35 kDa. Loss o f this protein after chlor­ amphenicol treatment leads to a corresponding reduction o f herbicide-binding sites as well as photosystem-II activity (measured by e.g. H20 -» silicom olybdate) and cellular photosynthesis. This correlation is quantitated by comparison o f the amount o f herbicide-binding protein (autoradiography), electron transport, and herbicide binding. An increase o f the binding constant after chloramphenicol treatment is evident.