616 



Mordhay Avron and Noun Shavit 



• ConlroKNo Mg.AOP.PO* ) 



40 60 



Salt concenlralion - M . 10 



Soil concentrotion — M » lO 



Fig. 7. The effect of Increasing salt concentration on the rate of several 



photoreductions. 



Details as described under Fig. 1, except that the reaction mixture contained 



only 13 jjmoles of sucrose per ml, and 1 |jmoie per ml of TRIS-HCI buffer at 



pH 7.8. The pH of all reaction mixtures was checked at the termination of 



the experiments, and was found to be between 7.5 - 7.8. The salt employed 



was either TRIS-HCI at pH 7.8 or NaCI. 



Fig. 8. The effect of salt concentration on the stimulation of the rate of 

 electron transport produced by the addition of phosphorylation-components 

 or an uncoupler. 

 Details as described under Fig. 7. 



to be related to the uncoupling effect of anions, recently described by Good , since the 

 latter effect occurred only at higher concentrations than the osmotic effect presently des- 

 cribed. 



Summary 



To summarize, we have indicated several properties related to the coupling of photophos- 

 phorylation to electron transport in isolated chloroplasts from swiss-chard leaves. The effect 

 of several new and more potent uncouplers was described. Their differential effect on 



