On the participation of chloride in bicarbonate‐induced reversal of anion inhibition of photosystem II electron transport in spinach thylakoids

Inhibition of electron transport through photosystem II (PS II) by formate (HCO − 2 ) or nitrite (NO − 2 ) in the presence or absence of chloride ions was studied. The inhibition induced by HCO − 2 or NO − 2 is overcome by HCO − 3 more in the presence, than in the absence of Cl − . The data on electron transport are supported by chlorophyll a fluorescence measurements. In experiments. In experiments in which water oxidation was blocked. Cl − was found to facilitate electron transport between bound quinone A (Q − A ) and the plastoquinone (PQ) pool. It can thus be concluded that in addition to the well known site of action of Cl − on water oxidation, another site of Cl − action is between Q − A and the PQ pool.