INFLUENCE OF OSMOLALITY OF THE MEDIUM ON PHOTOSYNTHETIC ELECTRON-TRANSPORT, PROTON FLUXES AND PHOTOPHOSPHORYLATION IN ISOLATED THYLAKOIDS

The high osmotic potential inhibition of photosynthetic electron trans port was determined to be related to membrane compaction rather than t o an effect of primary thylakoid volume changes. Osmotic inhibition of proton fluxes and phosphorylation were entirely due to osmotic inhibi tion of electron transport. The ATPase activity, the nature of couplin g and the rate constant of proton efflux were not influenced by osmoti c pressure, while the rate constant and the extent of proton influx we re inhibited by osmotic pressure.