The use of diphenylcarbazide as an electron donor coupled to the photoreduction of 2,6-dichlorophenolindophenol by tris-washed chloroplasts or subchloroplast fragments provides a simple and sensitive assay for photosystem 2 of chloroplasts. By varying the concentration of tris buffer at pH 8.0 during an incubation period it is shown that the destruction of oxygen evolution activity is accompani...

2,6-Diclhloroplleniolinidoplheol (D LP1P) is one of tlle mainy comnmloiinly) used electroni acceptors for the light-induced reactions in chloroplasts (2). Until recently, it has generally been assumed that it accepts electrons from the short-wavelengtlh pigment system 2 (PS2). Since the finding that indophenol reduction can be coupled with phlotophosphorylation [see review by Vernon and Avron (...

Pea chloroplasts isolated in salt media show decreased rates of 2:6 dichlorophenolindophenol (DCPIP) and ferricyanide reduction when depleted of CO(2) at pH values below 7.5. The greatest effect of CO(2) was on uncoupled systems. The incorporation of 10(-2), 2 x 10(-2) and 4 x 10(-2)m sodium acetate into the reaction mixtures progressively increased the bicarbonate concentration required for ha...

In isolated barley chloroplasts, the presence of 2 millimolar ZnSO(4) inhibits the electron transport activity of photosystem II, as measured by photoreduction of dichlorophenolindophenol, O(2) evolution, and chlorophyll a fluorescence. The inhibition of photosystem II activity can be restored by the addition of the electron donor hydroxylamine or diphenylcarbazide, but not by benzidine and MnC...

The flash patterns o f oxygen evolution after pre-illum ination by continuous light or by a flash sequence were com pared in etiochloroplasts and m ature chloroplasts o f barley. In both types o f plastids sub-saturating continuous illum ination o f som e seconds strongly affected the S3 but not the S2 state o f the oxygen-evolving com plex. This result is ascribed to efficient charge recom bin...