Myoglobin. Computer model of the protein myoglobin that contains the iron-containing haem group (not seen). Myoglobin consists of a chain of 153 amino acids folded into a globin molecule that has a similar function to the globin units that are found in haemoglobin. The haem group surrounds an iron atom that can temporarily bind to oxygen and store it for later use. Myoglobin is found in muscle tissue, where the stored oxygen is used during strenuous exercise. The structure of the globin protein protects the haem group (a coenzyme) from being oxidised and destroyed by the oxygen it carries. Myoglobin has a molecular weight of 17,800.