Structure of the ATP-synthase from chloroplasts and mitochondria studied by electron microscopy.

The structure of the ATP-synthase, F0F1, from spinach chloroplasts and beef heart mitochondria has been investigated by electron microscopy with negatively stained specimens. The detergent-solubilized ATP-synthase forms string-like structures in which the F0 parts are aggregated. In most cases, the F1 parts are arranged at alternating sides along the string. The F0 part has an approximate cylindrical shape with heights of 8.3 and 8.9 nm and diameters of 6.2 and 6.4 nm for the chloroplast and mitochondrial enzyme, respectively. The F1 parts are disk-like structures with a diameter of about 11.5 nm and a height of about 8.5 nm. The F1 parts are attached to the strings, composed of F0 parts, in most cases, with their smallest dimension parallel to the strings. The stalk connecting F0 and F1 has a length of 3.7 nm and 4.3 nm and a diameter of 2.7 nm and 4.3 nm for the chloroplast and mitochondrial enzyme, respectively.