UNCOUPLING OF PHOTOPHOSPHORYLATION BY NITROGENOUS BASES. NO CORRELATION Ofb UNCOUPLING WITH pKb and PARTITION COEFFICIENT

Twenty six nitrogenous compounds were tested for uncoupling activity from water to methylviologen in spinach chloroplasts. No correlation was found between photophosphorylation and pKb or partition coefficient. Thus basic strength is not related with uncoupling phenomena, suggesting that nitrogenous bases are not protonated during uncoupling. Steric effect is also unimportant for uncoupling. New discovered uncouplers were acetamide, hexylamide and trichloroacetamide, which are all very efficient uncouplers. Acetamide accelerates electron transport and decreases ATP synthesis. However, it increases net proton uptake at low concentration, and collapses proton gradient at high concentration. 1,12 Diaminododecane is also a very efficient uncoupler'but it does not have any relationship with other diamines tested; it causes reversible shrinkage to the chloroplast, which suggests that it is not a detergent type of uncoupler.