Myoglobin

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Myoglobin
Model of helical domains in myoglobin.
Gene code:	HUGO code: MB^[1]
Structure:	molecular structure^[2]
Recent publications:	role in human pathologies,^[3] gene knockout^[4]
protein type:	Hemoprotein
Functions:	oxygen storage/transport
Domains:	globin^[5]
Diseases:	kidney disease, vasospasm
Taxa expressing:	many metazoan phyla, Arhaea?^[6] protozoan/eubacterial?^[7]
Cell types:	muscle cells
Subcellular localization:	cytoplasm
covalent modifications	glycation?^[8] phosphorylation in whales?^[9]
Other names:	myoglobin-like proteins in microorganisms^[10]
Molecular interactions	oxygen, heme, carbon monoxide, nitric oxide
related articles:	X-ray crystallography, Secondary structure

$An X-ray diffraction image for the protein myoglobin.$

An X-ray diffraction image for the protein myoglobin.

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. With a molecular weight of 16,700 Daltons, it is the primary oxygen-carrying pigment of muscle tissues^[11]. Unlike the blood-borne hemoglobin, to which it is structurally related^[12], this protein does not exhibit cooperative binding of oxygen, since positive cooperativity is a property reserved for multimeric proteins. 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. In 1958, John Kendrew and associates successfully determined the structure of myoglobin by high-resolution X-ray crystallography.^[13] For this discovery, John Kendrew shared the 1962 Nobel Prize in chemistry with Max Perutz^[14].

[edit] Role in disease

Myoglobin is released from damaged muscle tissue (rhabdomyolysis), which has very high concentrations of myoglobin. The released myoglobin is filtered by the kidneys but is toxic to the renal tubular epithelium and so may cause acute renal failure.^[15].

Myoglobin is a sensitive marker for muscle injury, making it a potential marker for myocardial infarction in patients with chest pain^[16]. Its lack of specificity and the cost of the analysis has prevented its widespread use.

[edit] References

^ Symbol Report: MB. Retrieved on 2006-05-20.
^ Takano, T. "Structure of myoglobin refined at 2-0 A resolution. II. Structure of deoxymyoglobin from sperm whale". J. Mol. Biol. 110: 569-584.
^ Reeder, BJ, Svistunenko DA, Cooper CE, Wilson MT (Dec 2004). "The radical and redox chemistry of myoglobin and hemoglobin: from in vitro studies to human pathology". Antioxid Redox Signal 6 (6): 954-66. PMID 15548893.
^ Schlieper, G, Kim JH, Molojavyi A, Jacoby C, Laussmann T, Flogel U, Godecke A, Schrader J (Apr 2004). "Adaptation of the myoglobin knockout mouse to hypoxic stress". Am J Physiol Regul Integr Comp Physiol 286 (4): R786-92. PMID 14656764.
^ globin, with user query added. NCBI. Retrieved on 2006-05-20.
^ ST1818 hypothetical myoglobin [Sulfolobus tokodaii str. 7 GeneID: 1459874 Locus tag: ST1818]. NCBI (03-Dec-2005). Retrieved on 2006-05-20.
^ glbN Probable hemoglobin glbN [Mycobacterium tuberculosis H37Rv GeneID: 886402 Locus tag: Rv1542c]. NCBI (21-Mar-2006). Retrieved on 2006-05-20.
^ Roy, A, Sen S, Chakraborti AS (Feb 2004). "In vitro nonenzymatic glycation enhances the role of myoglobin as a source of oxidative stress". Free Radic Res. 38 (2): 139-46. PMID 15104207.
^ Stewart, JM, Blakely JA, Karpowicz PA, Kalanxhi E, Thatcher BJ, Martin BM (Mar 2004). "Unusually weak oxygen binding, physical properties, partial sequence, autoxidation rate and a potential phosphorylation site of beluga whale (Delphinapterus leucas) myoglobin". Comp Biochem Physiol B Biochem Mol Biol 137 (3): 401-12. PMID 15050527.
^ Wu, G, Wainwright LM, Poole RK (2003). "Microbial globins". Adv Microb Physiol 47: 255-310. PMID 14560666.
^ George A. Ordway and Daniel J. Garry (2004). "Myoglobin: an essential hemoprotein in striated muscle". Journal of Experimental Biology 207: pages 3441–3446. DOI:10.1242/jeb.01172.
^ Harvey Lodish, Arnold Berk, Lawrence S. Zipursky, Paul Matsudaira, David Baltimore and James Darnell (2000). “Evolutionary tree showing the globin protein family members myoglobin and hemoglobin”, Molecular Cell Biology, Fourth Edition, W. H. FREEMAN. ISBN 0-7167-3136-3.
^ JC Kendrew, G Bodo, HM Dintzis, RG Parrish, H Wyckoff, and DC Phillips (1958). "A Three-Dimensional Model of the Myoglobin Molecule Obtained by X-Ray Analysis". Nature 181 (4610): pages 662-666. DOI:10.1038/181662a0 PMID 13517261.
^ The Nobel Prize in Chemistry 1962
^ Toshio Naka, Daryl Jones, Ian Baldwin, Nigel Fealy, Samantha Bates, Hermann Goehl, Stanislao Morgera, Hans H. Neumayer and Rinaldo Bellomo (2005). "Myoglobin clearance by super high-flux hemofiltration in a case of severe rhabdomyolysis: a case report". Critical Care 9: pages R90–R95. DOI:10.1186/cc3034.
^ M. Weber, M. Rau, K. Madlener, A. Elsaesser, D. Bankovic, V. Mitrovic and C. Hamm (2005). "Diagnostic utility of new immunoassays for the cardiac markers cTnI, myoglobin and CK-MB mass". Clinical Biochemistry 38: pages 1027–1030. Entrez PubMed 16125162.