Myoglobin is a single-chain protein of 153 amino acids, containing a heme (iron-containing porphyrin) group in the center. With a molecular weight of 16,700 Daltons, it is the primary oxygen-carrying pigment of muscle tissues. Unlike the blood-borne hemoglobin, to which it is structurally related, this protein does not exhibit cooperative binding of oxygen. Instead, the binding of oxygen by myoglobin is unaffected by the oxygen pressure in the surrounding tissue. In 1957, John Kendrew and associates successfully determined the structure of myoglobin by high-resolution X-ray crystallography.

3D structure of the Myoglobin protein: alpha helices are shown in colour, and random coil in white, there are no beta sheets in shown. This protein was the first to have its structure solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, which led to them receiving a Nobel Prize in Chemistry in 1962.

Role in disease

Myoglobin has been implicated as a cause of acute renal failure following damage to muscle tissue (e.g. rhabdomyolysis, severe crush trauma, malignant hyperthermia, status epilepticus and neuroleptic malignant syndrome), due to its toxicity to renal tubular epithelium.

Myoglobin is a sensitive marker for muscle injury, making it a potential marker for myocardial infarction in patients with chest pain. Its specificity and the cost of the analysis has prevented its widespread use.

During muscle death due to infarction, myoglobin is released, which is toxic to the kidneys. If it is misdiagnosed, it can cause much worse conditions, such as cardiac arrest.


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