Study of three-dimensionally ordered structures of intact mitochondria by small-angle neutron scattering

Abstract

The ultrastructure of cristae of intact mitochondria, in which the activity of the oxidative phosphorylation system was retained, was investigated by small-angle neutron scattering. Osmotic swelling of organelles was found to cause ultrastructural rearrangements of the inner mitochondrial membrane in rat liver and heart mitochondria. This process was accompanied by the appearance of diffraction peaks indicative of the formation of ordered structures. The lamellar packing of the membranes in heart mitochondria, which is observed under normal conditions, was found to undergo a transition to a nonlamellar hexagonal packing, whose scattering curve shows two peaks with the scattering vectors characterized by a spacing ratio of 1:√3. The electron-microscopy results confirm the possibility of the formation of a hexagonal packing of the inner membrane in heart mitochondria.