Uncoupling Phosphorylation in Spinach Chloroplasts by Absence of Cations.

During attempts to prepare active fragments of spinach chloroplasts, we observed major losses of phosphorylative activity following suspension of the chloroplasts in water. This damage was traced to treatments which probably had the effect of removing cations from the chloroplasts, rather than to a simple physical disruption. Indeed, chloroplast fragments have been used successfully in studies of phosphorylation for a considerable time by now (3,18). Evi. dence for the basis of the observed damage and characteristics of the inactivated chloroplasts will be described below.