Myoglobin

Myoglobin (symbol Mb or MB) is an <a href="/facts/Iron/QK1JYy8E">iron</a>- and <a href="/facts/Oxygen/acyn6o8r">oxygen</a>-binding <a href="/facts/Protein/Jxmagu3E">protein</a> found in the cardiac and <a href="/facts/Skeletal_muscle/en1tVYFN">skeletal</a> <a href="/facts/Muscle/dmxrL8pH">muscle tissue</a> of vertebrates in general and in almost all mammals. Myoglobin is distantly related to <a href="/facts/Hemoglobin/RsD1MzYA">hemoglobin</a>. Compared to <a href="/facts/Hemoglobin/RsD1MzYA">hemoglobin</a>, myoglobin has a higher affinity for oxygen and does not have <a href="/facts/Cooperative_binding/EVjB8JPf">cooperative binding</a> with oxygen like hemoglobin does. Myoglobin consists of non-polar amino acids at the core of the globulin, where the heme group is non-covalently bounded with the surrounding polypeptide of myoglobin. In humans, myoglobin is found in the bloodstream only after <a href="/facts/Strain_(injury)/wnAWmHWb">muscle injury</a>.
High concentrations of myoglobin in muscle cells allow organisms to hold their breath for a longer period of time. Diving mammals such as whales and seals have muscles with particularly high abundance of myoglobin. Myoglobin is found in Type I muscle, Type II A, and Type II B; although many older texts describe myoglobin as not found in <a href="/facts/Smooth_muscle_tissue/mpcpTsHp">smooth muscle</a>, this has proved erroneous: there is also myoglobin in smooth muscle cells.
Myoglobin was the first protein to have its three-dimensional structure revealed by <a href="/facts/X-ray_crystallography/WtI0F5DN">X-ray crystallography</a>. This achievement was reported in 1958 by <a href="/facts/John_Kendrew/KwWW3Kul">John Kendrew</a> and associates. For this discovery, Kendrew shared the 1962 <a href="/facts/Nobel_Prize_in_Chemistry/8Nb8Ajjy">Nobel Prize in Chemistry</a> with <a href="/facts/Max_Perutz/HGgPx1Gh">Max Perutz</a>. Despite being one of the most studied proteins in biology, its physiological function is not yet conclusively established: mice genetically engineered to lack myoglobin can be viable and fertile, but show many cellular and physiological adaptations to overcome the loss. Through observing these changes in myoglobin-depleted mice, it is hypothesised that myoglobin function relates to increased oxygen transport to muscle, and to oxygen storage; as well, it serves as a scavenger of <a href="/facts/Reactive_oxygen_species/GpwSRugH">reactive oxygen species</a>.
In humans, myoglobin is encoded by the MB <a href="/facts/Gene/e1swwPY6">gene</a>.
Myoglobin can take the forms oxymyoglobin (MbO2), carboxymyoglobin (MbCO), and <a href="/facts/Metmyoglobin/NsWGnawu">metmyoglobin</a> (met-Mb), analogously to hemoglobin taking the forms oxyhemoglobin (HbO2), <a href="/facts/Carboxyhemoglobin/pzv2kCQe">carboxyhemoglobin</a> (HbCO), and <a href="/facts/Methemoglobin/eTPQFl0A">methemoglobin</a> (met-Hb).

Myoglobin open-in-new

Myoglobin