INDUCTION OF AN ELECTROGENIC TRANSFER OF MONOVALENT CATIONS (K+, NH+4) IN THYLAKOID MEMBRANES BY N,N'-DICYCLOHEXYLCARBODIIMIDE

The effect of N,N'-dicyclohexylcarbodiimide (DCCD) on photosynthetic electron transport and light-induced NH4+ and K+ uptake in the presence of ammonium or nigericin was studied. DCCD alone had no effect on either the electron transport or the uptake of protons. The simultaneous action of DCCD and low concentrations of ammonium or nigericin was shown to lead to a significant increase in the electron transport rate and a decrease in the steady-state uptake value of H+ and NH4+ or K+. The effect of DCCD on these processes was compared with the effect of the ionophore, valinomycin, which transports potassium and ammonium cations through membranes. The conclusion was made that 1.0-1.5 mol DCCD per mol chlorophyll activated the transfer system of monovalent cations (K+ and NH4) in thylakoid membranes.