Cytochromes contain 3 Iron
Cytochromes are heme-containing proteins. Three varieties are recognized, cytochromes a, cytochromes b, and cytochromes c. They differ with respect to the substituents on the periphery of the heme. Cytochromes function as electron relays, exploiting the switching of the iron centers from ferrous (Fe(II)) to ferric(Fe(III)). [1] In addition to cytochromes a, b, and c, many other cytochromes exist. These other cytochromes include cytochrome oxidase and cytochrome P450.