Effect of urea and distilled water on the structure of the thylakoid system

On the basis of structural data, an attempt is made to substantiate the hypothesis that in a thylakoid membrane, there exists an integral continuous network of intramembrane, lateral protein-protein interactions. It is shown that the forces determining the extent of flattening of the thylakoid system and the forces responsible for the packing of thylakoids in granas act independently. These two discrete groups of bonds, lateral bonds of the external leaflet of the membrane and the bonds of intermembrane stacking, provide a peculiar configuration of the system of internal chloroplast membranes, namely, the granal packing and the extent of flattening of the thylakoid system.