Myoglobin
Model of helical domains in myoglobin. [1]
Available structures: 1m6c, 1m6m, 1mdn, 1mnh, 1mni, 1mnj, 1mnk, 1mno, 1mwc, 1mwd, 1myg, 1myh, 1myi, 1myj, 1pmb, 1yca, 1ycb, 2mm1
Identifiers
Symbol(s)	MB; MGC13548; PVALB
External IDs	OMIM: 160000 MGI: 96922 HomoloGene: 3916
RNA expression pattern
More reference expression data
Orthologs
	Human	Mouse
Entrez	4151	17189
Ensembl	ENSG00000198125	ENSMUSG00000018893
Uniprot	P02144	Q3UVB1
Refseq	NM_005368 (mRNA) NP_005359 (protein)	NM_013593 (mRNA) NP_038621 (protein)
Location	Chr 22: 34.33 - 34.35 Mb	Chr 15: 76.84 - 76.88 Mb
Pubmed search	[1]	[2]

Myoglobin is a single-chain globular protein of 153 amino acids, containing a heme (iron-containing porphyrin) prosthetic group in the center around which the remaining apoprotein folds. The Human Genome Organisation (HUGO is an organization involved in the Human Genome Project, a project about mapping the human genome The Mouse Genome Informatics (MGI website is run by The Jackson Laboratory. HomoloGene, a tool of the National Center for Biotechnology Information (NCBI is a system for automated detection of homologs (similarity attributable to descent The Entrez Global Query Cross-Database Search System is a powerful Federated search engine or Web portal that allows users to search many discrete Health sciences Ensembl is a joint scientific project between the European Bioinformatics Institute and the Wellcome Trust Sanger Institute, which was launched in 1999 in response to the imminent UniProt is the uni versal prot ein resource a central repository of Protein data created by combining Swiss-Prot, TrEMBL PubMed is a free search engine for accessing the MEDLINE database of citations and abstracts of biomedical research articles In Biochemistry and Chemistry, the tertiary structure of a Protein or any other Macromolecule is its three-dimensional structure as defined Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this A heme ( American English) or haem ( British English) is a Prosthetic group that consists of an Iron atom contained in the center of Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 A porphyrin is a heterocyclic Macrocycle derived from four Pyrroline subunits interconnected via their α carbon atoms via Methine bridges (=CH- A prosthetic group is a non-protein (non- Amino acid) component of a Conjugated protein that is important in the protein's biological activity It has a molecular weight of 16,700 daltons, and is the primary oxygen-carrying pigment of muscle tissues. The unified atomic mass unit ( u) or Dalton ( Da) or sometimes universal mass unit, is an unit of Mass used to express Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the For the drug referred to as "pigment" see Black tar heroin. Muscle (from Latin musculus, diminutive of mus "mouse" is contractile tissue of the body and is derived from the ^[2] Unlike the blood-borne hemoglobin, to which it is structurally related,^[3] this protein does not exhibit cooperative binding of oxygen, since positive cooperativity is a property of multimeric/oligomeric proteins only. Hemoglobin ( also spelled haemoglobin and abbreviated Hb or Hgb) is the Iron -containing Oxygen -transport Metalloprotein In Biochemistry, a Macromolecule exhibits cooperative binding if its Affinity for its ligand changes with the amount of ligand already bound In Chemistry, an oligomer consists of a limited number of Monomer units (ολιγος or oligos is Greek for "a few" in contrast to a Instead, the binding of oxygen by myoglobin is unaffected by the oxygen pressure in the surrounding tissue. Myoglobin is often cited as having an "instant binding tenacity" to oxygen given its hyperbolic oxygen dissociation curve. Dissociation in Chemistry and Biochemistry is a general process in which ionic compounds ( complexes, Molecules, or Salts) separate High concentrations of myoglobin in muscle cells allow organisms to hold their breaths longer. In 1958, John Kendrew and associates successfully determined the structure of myoglobin by high-resolution X-ray crystallography. Sir John Cowdery Kendrew ( 24 March 1917 &ndash 23 August 1997) was an English Biochemist and crystallographer X-ray crystallography is a method of determining the arrangement of Atoms within a Crystal, in which a beam of X-rays strikes a crystal and scatters ^[4] For this discovery, John Kendrew shared the 1962 Nobel Prize in chemistry with Max Perutz. The Nobel Prize in Chemistry (Nobelpriset i kemi is awarded annually by the Royal Swedish Academy of Sciences to scientists in the various fields of Chemistry. Max Ferdinand Perutz, OM ( May 19 1914, Vienna, Austria – February 6 2002, Cambridge, ^[5] The human version of this gene is MB. Myoglobin is a single-chain globular Protein of 153 Amino acids containing a Heme ( Iron -containing Porphyrin) Prosthetic Despite being one of the most studied proteins in biology, its true physiological function is not yet conclusively established: mice genetically engineered to lack myoglobin are viable and show no obvious defects.

Contents 1 Meat color 2 Role in disease 3 Structure and bonding 4 See also 5 References 6 Further reading 7 External links

Meat color

Myoglobin forms pigments responsible for making meat red. For the drug referred to as "pigment" see Black tar heroin. For mammal meat see Red meat. For the band see Red Meat (band. The color that meat takes is partly determined by the charge of the iron atom in myoglobin and the oxygen attached to it. When meat is in its raw state, the iron atom has a charge of +2 and is bound to O₂, an oxygen molecule. Meat cooked well done is brown because the iron atom has a charge of +3, having lost an electron, and is now bound to a water molecule (H₂O). Temperature, or doneness, is a description of how thoroughly cooked a cut of meat is based on the color juiciness and internal temperature when served Under some conditions, meat can also remain pink all through cooking, despite being heated to high temperatures. If meat has been exposed to nitrites, it will remain pink because the iron atom is bound to NO, nitric oxide (true of, e. The nitrite Ion is NO2− The anion is bent being Isoelectronic with O3. Nitric oxide or nitrogen monoxide is a Chemical compound with Chemical formula N[[Oxygen O]] g. , corned beef or cured hams). In the US and Canada Corned beef has two meanings One refers to a cut of Beef (usually Brisket, but sometimes round or silverside) Ham is the Thigh and Rump of Pork, cut from the Haunch of a Pig or Boar. Grilled meats can also take on a pink "smoke ring" that comes from the iron binding a molecule of carbon monoxide. A smoke ring is a visible Vortex ring formed by expelling Smoke through an opening ^[6] Raw meat packed in a carbon monoxide atmosphere also shows this same pink "smoke ring" due to the same molecular process. Notably, the surface of the raw meat also displays the pink color, which is usually associated in consumers' minds with fresh meat. This artificially-induced pink color can persist in the meat for a very long time, reportedly up to one year. ^[7] Hormel and Cargill are both reported to use this meat-packing process, and meat treated this way has been in the consumer market since 2003. ^[8] Myoglobin is found in Type I muscle, Type II A and Type II B, but most texts consider myoglobin not to be found in smooth muscle.

Role in disease

Myoglobin is released from damaged muscle tissue (rhabdomyolysis), which has very high concentrations of myoglobin. Rhabdomyolysis is the rapid breakdown ( Lysis) of Skeletal muscle tissue ( rhabdomyo) due to injury to muscle tissue The released myoglobin is filtered by the kidneys but is toxic to the renal tubular epithelium and so may cause acute renal failure. The kidneys are complicated organs that have numerous biological roles Acute renal failure ( ARF) also known as acute kidney failure or acute kidney injury, is a rapid loss of Renal function due to damage to the ^[9]

Myoglobin is a sensitive marker for muscle injury, making it a potential marker for heart attack in patients with chest pain. Myocardial infarction ( MI or AMI for acute myocardial infarction) also known as a heart attack, occurs when the blood supply In Medicine, chest pain is a Symptom of a number of serious conditions and is generally considered a Medical emergency. ^[10] CK-MB and TnT is used in combination with ECG, and the clinical signs to diagnose AMI

Structure and bonding

Myoglobin contains a porphyrin ring with an iron center. A porphyrin is a heterocyclic Macrocycle derived from four Pyrroline subunits interconnected via their α carbon atoms via Methine bridges (=CH- There is a proximal histidine group attached directly to the iron center, and a distal histidine group on the opposite face, not bonded to the iron. Histidine (abbreviated as His or H) is one of the 20 standard Amino acids present in Proteins In the Nutritional sense in

Many functional models of myoglobin have been studied. One of the most important is that of picket fence porphyrin by James Collman. This model was used to show the importance of the distal prosthetic group. A prosthetic group is a non-protein (non- Amino acid) component of a Conjugated protein that is important in the protein's biological activity It serves three functions:

1. to form hydrogen bonds with the dioxygen moiety, increasing the O₂ binding constant
2. to prevent the binding of carbon monoxide, whether from within or without the body. A hydrogen bond results from a Dipole-dipole force between an Electronegative atom and a Hydrogen atom bonded to Nitrogen, Oxygen Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. Carbon monoxide binds to iron in an end-on fashion, and is hindered by the presence of the distal histidine, which forces it into a bent conformation. Histidine (abbreviated as His or H) is one of the 20 standard Amino acids present in Proteins In the Nutritional sense in CO binds to heme 23,000 times better than O₂, but only 200 times better in hemoglobin and myoglobin. Hemoglobin ( also spelled haemoglobin and abbreviated Hb or Hgb) is the Iron -containing Oxygen -transport Metalloprotein Oxygen binds in a bent fashion, which can fit with the distal histidine. ^[11]
3. to prevent irreversible dimerization of the oxymyoglobin with another deoxymyoglobin species

See also

• Hemoglobin
• Neuroglobin
• Cytoglobin
• Hemoprotein

References

Further reading

External links

• The Myoglobin Protein
• Protein Database featured molecule
• Online 'Mendelian Inheritance in Man' (OMIM) 160000 human genetics
• Which Cut Is Older? (It's a Trick Question) New York Times, February 21, 2006 article regarding meat industry use of carbon dioxide to keep meat looking red. The Mendelian Inheritance in Man project is a Database that catalogues all the known Diseases with a genetic component, and—when possible—links them
• Stores React to Meat Reports New York Times, March 1, 2006 article on the use of carbon monoxide to make meat appear fresh.

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