myoglobin facilitates the oxygen use and storage in the muscles; and cytochromes
transport electrons. Iron is also an integral part of enzymes in various tissues. The average 70-kg adult body contains around 4200 mg of iron ions. The majority (65%) can be found as haemoglobin or myoglobin, which
is classified as the functional iron .
Myoglobin consists of a monomeric protein chain containing one protoporphyrin group as the functional
unit.Within myoglobin, the iron centre is coordinated by the four nitrogen groups of the porphyrin in addition
to the coordination of a fifth nitrogen centre from a histidine (His) group. The functional unit containing the
Fe(II) centre is called a haeme group and is a square-based pyramidal complex. During the oxygen binding
mechanism, O2 will enter trans to the His group to give an octahedrally coordinated iron species.
Myoglobin from human heart has been used as a negative control in monitoring isoAsp formation during storage. It has also been used as an antigen in the study to identify self-antigens recognized by serum autoantibodies from unimmunized mice strains.
A protein-iron-porphyrin moleculesimilar to hemoglobin. The chief difference isthat myoglobin complexes one heme group permolecule, whereas hemoglobin complexes fourheme groups.
A globular
protein formed of a heme group and a single
polypeptide chain. It occurs in muscle
tissue where it acts as an oxygen store.
Myoglobin?is a heme-related, low-molecular-weight protein. It is mainly found in cardiac and skeletal muscle.
Myoglobin may help to increase diffusion and also stores O2 in oxidative muscle. It can momentarily act as an oxygen reservoir to supply oxygen when there is inadequate blood oxygen delivery at the time of intense muscular activity.
Human Myoglobin produced in Human Cardiac Tissues having a molecular mass of 17.5kDa.
Myoglobin is released from recently injured myocardial cells within a few hours of Infarction. Peak levels are reached more quickly than CK-MB or Troponin complex.
Myoglobin is a member of the globin superfamily and can be found in skeletal and cardiac muscles. It is a haemoprotein that contributs to intracellular oxygen storage and transcellular facilitated diffusion of oxygen. Myoglobin has a single-chain globular structure of 153 amino acids, containing a heme prosthetic group (iron-containing porphyrin) in the core around which the remaining apoprotein folds. Myoglobin has 8 alpha helices and a hydrophobic core. Myoglobin’s molecular weight is 16.7 kDa, and it is the primary oxygen-carrying pigment of muscle tissues. The binding of oxygen in myoglobin is different from the cooperative oxygen binding in hemoglobin, since positive collaboration is a property of multimeric/oligomeric proteins only. Instead, the binding of oxygen by myoglobin is uninfluenced by the oxygen pressure in the surrounding tissue. Myoglobin is frequently referred to as having an "instant binding tenacity" to oxygen given its hyperbolic oxygen dissociation curve. Different organisms are able to hold their breaths longer due to high concentrations of myoglobin in their muscle cells. Myoglobin is responsible for the pigments that make meat red. The color of the meat is partly determined by the charge of the iron atom in myoglobin and the oxygen attached to it. Myoglobin is found in Type I muscle, Type II A and Type II B, but it is mostly deemed that myoglobin is not found in smooth muscle. Myoglobin is discharged from damaged muscle tissue (rhabdomyolysis), which contains very high concentrations of myoglobin. Even though the released myoglobin is filtered by the kidneys, it is toxic to the renal tubular epithelium and thus may cause acute renal failure.
