When bacteria oxidize substrates with terminal electron acceptors such as molecular oxygen, sulfate, and nitrate, the electrons liberated from the substrates are transferred to the acceptors through cytochromes. Cytochromes belong to hemoproteins, but not all the hemoproteins are cytochromes. There are roughly two groups in the hemoproteins. Hemoglobin typifies one group while cytochrome typifies the other. Hemoglobin functions only when the iron in the heme is ferrous state [Fe(II)], while cytochrome functions by varying the iron valency in the heme. The heme iron of cytochrome varies in most cases between ferrous iron [Fe(II)] and ferric iron [Fe(III)]; cytochrome functions by oxidation and reduction of the heme iron.
KeywordsMolecular Oxygen Heme Iron Prosthetic Group Terminal Oxidase Pseudomonas Stutzeri
Unable to display preview. Download preview PDF.