Use

myoglobin facilitates the oxygen use and storage in the muscles; and cytochromes transport electrons. Iron is also an integral part of enzymes in various tissues. The average 70-kg adult body contains around 4200 mg of iron ions. The majority (65%) can be found as haemoglobin or myoglobin, which is classified as the functional iron . Myoglobin consists of a monomeric protein chain containing one protoporphyrin group as the functional unit.Within myoglobin, the iron centre is coordinated by the four nitrogen groups of the porphyrin in addition to the coordination of a fifth nitrogen centre from a histidine (His) group. The functional unit containing the Fe(II) centre is called a haeme group and is a square-based pyramidal complex. During the oxygen binding mechanism, O2 will enter trans to the His group to give an octahedrally coordinated iron species.