Serum Myoglobin

Excerpt

Myoglobin is a dark red cytoplasmic hemoprotein found only in cardiac myocytes and oxidative skeletal muscle fibers. It belongs to the super globin family of proteins. It comprises a single polypeptide chain of 154 amino acids and a porphyrin ring containing a central ferrous iron molecule. Similar to hemoglobin, myoglobin functions to reversibly bind oxygen and can form oxymyoglobin, carboxy myoglobin, or metmyoglobin. Unlike hemoglobin, however, myoglobin has only one binding site for oxygen, the affinity of which is comparatively very high. As a result, myoglobin can receive oxygen from hemoglobin at the tissue level via the Bohr effect and either store oxygen or deliver it to muscle cells during periods of hypoxia, anoxia, or increased metabolic activity.