Preservation of photophosphorylation in glycerinated chloroplasts.

Abstract

Spinach chloroplasts, when stored in vitro in 50% glycerol at −20° have been found to retain the capacity for cyclic and non-cyclic photophosphorylation for several weeks, whereas this activity is quickly lost in control experiments. A time study made of the decline in light-triggered ATP hydrolysis and photophosphorylation for 3 electron-flow systems revealed that ATP synthesis was more labile than hydrolysis. Photosynthetic electron flow (NADP+ reduction) and light-induced comformational changes are lost much more slowly upon storage of glycerinated chloroplasts than ATP hydrolysis or synthesis. Hence light-induced conformational changes are more a sensitive test for assessing the occurrence of the high-energy state of spinach chloroplasts than the reactions involving ATP hydrolysis or synthesis.