The Inhibition of Photosynthetic Electron Flow in Chloroplasts by the Dinitrophenylether of Bromo-or Iodo-nitrothymol

Abstract

The O -dinitrophenyl derivatives of 2 -bromo-and 2-iodo-4-nitrothymol are inhibitors of photo­ synthetic electron flow from water to NADP or methylviologen, yielding 50% inhibition at 0.5 μм. Photoreductions by either photosystem I or photosystem II alone are not inhibited. The inhibition site is bypassed by TM PD. The inhibition pattern identical to the one of dibromothymoquinone. It is reduction of plastoquinone.