One of the most important proteins in the human body is MYOGLOBIN. Today we are discussing Myoglobin in this post. Myoglobin is found in muscle tissue, where it binds oxygen, helping to provide extra oxygen to release energy to power muscular contractions.
Let us come to the history of Myoglobin, Myoglobin was the first protein they determined whose structure. In 1958, Max Perutz and John Kendrew determined the 3D structure of myoglobin by X-ray crystallography. In 1962 a share of the Nobel Prize for Chemistry was awarded to John C. Kendrew for work, using the technique of X-ray diffraction, that permitted construction of a three-dimensional model of crystalline sperm-whale myoglobin.
Basic points of Myoglobin:
- Myoglobin (myoG-Muscle; globinG=a type of protein) is a relatively small, oxygen-binding heme protein, found in muscle cells.
- Myoglobin is a monomeric protein that has 153 amino acids residues.
- It comprises eight α-helix connected through the turns with an Oxygen binding site.
- Out of 153 amino acids, 121 (79%) are present on the helical regions and it distributes the remaining 32 amino acids over the non-helical areas.
- It has a globular structure.
- The molecular weight of Myoglobin is 16,700, is a compact macromolecule with oblate, spheroid shaped macromolecule.
- The overall molecular dimensions are 45 X 35 X 25 Ao.
- Myoglobin contains a heme (prosthetic) group responsible for its main function (carrying of oxygen molecules to muscle tissues) and Globin protein.
- Myoglobin is a protein found in muscles that bind oxygen with its heme group like hemoglobin.
- Heme group comprises protoporphyrin organic component and an iron atom in its center.
- The heme group gives muscle and blood their distinctive red color.
- Oxidation of the iron atom (Fe2+ -> Fe3+) is mainly responsible for the color of muscle and blood.
- The prosthetic heme group binds to proximal histidine group while a distal histidine group interacts on the other side of the plane in the structure.
- Myoglobin without its heme prosthetic group is designated apo-myoglobin. The main function of apo-myoglobin is to provide a hydrophobic environment for the heme group.
When muscle tissue is damaged, very large concentrations of myoglobin enters the kidneys. When this happens, myoglobin is then considered highly toxic and may contribute to acute renal failure. Muscle injury is commonly associated with the release of myoglobin and is known to be the cause of heart attacks and many other myoalgia. Studies have shown that acute myocardial infarction can be detected with the help of the monitoring of creatine kinase and troponin by electrocardiogram.