myoglobin


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myoglobin

(mī'əglō`bĭn), proteinprotein,
any of the group of highly complex organic compounds found in all living cells and comprising the most abundant class of all biological molecules. Protein comprises approximately 50% of cellular dry weight.
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 molecule isolated from the cells of vertebrate skeletal muscle that is both a structural and functional relative of hemoglobinhemoglobin
, respiratory protein found in the red blood cells (erythrocytes) of all vertebrates and some invertebrates. A hemoglobin molecule is composed of a protein group, known as globin, and four heme groups, each associated with an iron atom.
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, the oxygen-transport protein of the blood of higher animals. Myoglobin, which is composed of a single polypeptide chain of 153 amino acidamino acid
, any one of a class of simple organic compounds containing carbon, hydrogen, oxygen, nitrogen, and in certain cases sulfur. These compounds are the building blocks of proteins.
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 residues, has the ability to store oxygen by binding it to an iron atom; iron is part of myoglobin's essential chemical composition. The complete amino acid sequence of myoglobin has been determined; it is a relatively small protein with a molecular weight of approximately 17,000 grams per mole. The distribution of myoglobin among the higher animals is a reflection of its physiological function. It is found abundantly in the tissues of diving mammals, e.g., the whale, the seal, and the dolphin. High concentrations of myoglobin in these animals presumably allows them to store sufficient oxygen to remain underwater for long periods. Myoglobin is found abundantly in man only in cardiac muscle, which, by virtue of its essential function, must possess the capacity for continued activity when environmental oxygen concentrations are low. Myoglobin has been investigated intensely and is the first protein molecule to have been completely described in terms of its three-dimensional geometry. This achievement won the British scientist John Kendrew a share in the 1962 Nobel Prize for Chemistry.

Myoglobin

 

a globular protein that stores molecular oxygen in muscles and delivers it to the oxidative cell systems.

Myoglobin is the first protein whose structure was elucidated by X-ray diffraction analysis (J. Kendrew and his associates, 1957–60). It consists of a single polypeptide chain (about 70 percent of the 153 amino-acid residues are included in the spiral parts). As in hemoglobin, the active center of the myoglobin molecule that binds O2 is heme. The molecular weight of myoglobin is 17,000. The spatial structure of myoglobin resembles the beta chain of hemoglobin. Myoglobin combines reversibly with oxygen even at low partial pressures of oxygen. This is of great physiological importance: the partial pressure of oxygen decreases sharply during muscle contraction as a result of compression of the capillaries, and it is at this very moment that the oxygen needed by the working muscle is released from myoglobin.

The muscles of vertebrates contain about two percent myoglobin per dry tissue mass; the muscles of marine animals capable of staying under water a long time (seal, whale, dolphin) contain about 20 percent. Myoglobin determines the color of muscles in vertebrates.

REFERENCES

Verbolovich, P. A. Mioglobin i ego rol’ v fiziologii i patologii zhivotnykh i cheloveka. Moscow, 1961.
Kendrew, J. C. “Mioglobin i struktura belkov.” Biofizika, 1963, vol. 8, no. 3.

V. O. SHPIKITER

myoglobin

[¦mī·ə¦glō·bən]
(biochemistry)
A hemoglobinlike iron-containing protein pigment occurring in muscle fibers. Also known as muscle hemoglobin; myohemoglobin.
References in periodicals archive ?
Dr Michael Berenbrink, from the University's Institute of Integrative Biology, who led the international team, explains: "We studied the electrical charge on the surface of myoglobin and found that it increased in mammals that can dive underwater for long periods of time.
The myoglobin showed quasireversible electrochemical behavior with a formal potential of -48 mV (vs Ag/AgCl), cathodic and anodic peaks were not observed using the bare graphite electrode.
Similar to hemoglobin and myoglobin, neuroglobin holds on to oxygen.
In this patient, rhabdomyolysis is evidenced by the increased plasma myoglobin level as well as the appearance of cola-colored urine which is characteristic of myoglobinuria.
Water holding capacity (WHC), moisture, electron microscopic observation, assay of heme pigment (myoglobin concentration) and myoglobin analysis using SDS-PAGE were carried out using a portion of all samples.
Prof Cossins said: "This was such an unexpected finding because myoglobin is the world's most famous protein.
Levels of muscular enzymes CK, myoglobin, ALT, AST, LDH and aldolase were extremely elevated, and a urinalysis established the presence of myoglobulinuria.
3 and anion gap of 30; urine drug screen: positive for marijuana and amphetamines; CPK 31,445 and myoglobin 175,234.
In contrast to nonspecific elevations of myoglobin and creatine kinase MB (CK-MB) in athletes due to exertional rhabdomyolysis of trained skeletal muscle(1,2), reported increases in cardiospecific troponins after competition may indicate silent injury to the myocardium (3,4,5,6,7,8).
Parallel studies of the same derivatives of horseradish peroxidase and myoglobin have also been carded out to calibrate the activity of DHP by comparison to typical peroxidase and globin proteins.
Andrew Clarke, a meat scientist at the university, explains that poultry most commonly acquires a pinkish color near surfaces when combustion gases produced in a gas oven react chemically with myoglobin, the protein found in meat that creates a red pigment.