myoglobin my·o·glo·bin (mī'ə-glō'bĭn)
The oxygen-transporting protein of muscle, resembling blood hemoglobin in function but with only one heme as part of the molecule and with one fourth the molecular weight. Also called muscle hemoglobin.
An iron-containing protein found in muscle fibers, consisting of heme connected to a single peptide chain that resembles one of the subunits of hemoglobin. Myoglobin combines with oxygen released by red blood cells and transfers it to the mitochondria of muscle cells, where it is used to produce energy.