|The cytochromes (a, a3, b, c1, and c) are a group of intracellular heme-containing proteins which are involved in
electron transport. They are widely distributed in nature in both plant and animal cells. The heme iron is located in the
center of the protoporphyrin IX ring structure and is bonded to the pyrrole nitrogens.
Of the various mitochondrial cytochromes, cytochrome C has been extensively studied. It consists of a single
polypeptide chain with heme as a prosthetic group. Mammalian heart muscle is a rich source of cytochrome C. The
cytochrome C prepared from equine heart muscle has a molecular weight of 13,000.
Purity of cytochrome C is established by disc electrophoresis on polyacrylamide gel.