Transmission electron micrograph of an unstained, unfixed cytochrome c oxidase crystal prepared from beef heart mitochondria imaged in the frozen hydrated state. A crystalline organization is seen within the ovoid structure in the left portion of the image.
Samples of cytochrome c oxidase in suspension were applied to holey carbon films in a water saturated atmosphere, blotted, and plunged into a cryogen consisting of a mixture of 95% propane and 5% isopentane cooled by liquid nitrogen. Grids were examined using a Philips 420T TEM and images recorded at 46KX in the frozen hydrated state on Kodak SO-163 film. Negatives were scanned with a pixel size of 20x20 micrometers. See also: Frey TG and Murray JM 1994. Electron microscopy of cytochrome c oxidase crystals. J Mol Biol 237:275-297.