Comparative X-ray diffraction and electron microscope studies of isolated mitochondrial membranes

Abstract

Inner membranes and outer membranes from rat liver mitochondria were isolated using monoamine oxidase and rotenone-insensitive NADH-cytochrome c oxidoreductase as marker enzymes for outer membrane and succinate dehydrogenase for inner membrane. X-ray diffraction studies have allowed a comparison of structural parameters of the two membranes. Serial diffraction patterns obtained during controlled dehydration of the membrane preparations have been interpreted with the aid of corresponding electron micrographs in terms of an initial close packing of the membranes into lamellar arrays followed by molecular rearrangement in the system as structurally essential water is removed. Comparisons of corresponding patterns from inner and outer membrane preparations have emphasized a fundamental similarity in membrane structure with differences only in detail. No evidence for a subunit structure was obtained for either membrane.