[Disintegration and fractionation of barley chloroplast membranes at different concentrations of digitonin and chloroplasts].

Chloroplasts pretreated with digitonin were fractionated by electrophoresis in order to study the arrangement of chloroplast membranes. Different types of particles resulting from the electrophoresis are shown to be due to fractionation of the chloroplast membranes of the same type rather than to the isolation of particular types from the chloroplasts of different ages. The stopped-flow measurement of quickly changing light scattering demonstrated that the membrane solubilization increased with the increase in the digitonin concentration. Meanwhile the fractionation result (the amount of particles in the electrophoretic zones and their spectral properties) remain very similar over a wide range of the detergent and chloroplast concentrations. This is explained by the fact that the increasing detergent concentrations do not cause particle destruction. Thus the method used revealed the particles which different from one another before they were isolated from the membrane. They are fractionated following the natural boundaries between them and the containing membrane. In other words, chloroplast membranes have a discrete set of submembrane particles of different types.