Myoglobin

	Email		Print
	Bookmark		Link

Myoglobin

Myoglobin is a single-chain

Tertiary structure

In biochemistry and chemistry, the tertiary structure of a protein or any other macromolecule is its three-dimensional structure, as defined by the atomic coordinates....
globular protein

Protein

Proteins are organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid Residue ....
of 153 amino acid

Amino acid

In chemistry, an amino acid is a molecule containing both amine and carboxyl functional groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent....
s, containing a heme

Heme

A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin....
(iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. Iron is a Group 8 element and period 4 element. Iron is lustrous and silvery in color....
-containing porphyrin

Porphyrin

Porphyrins are a group of chemical compounds of which many occur in nature, such as in green leaves and red blood cells, and in bio-inspired synthetic catalysts and devices....
) prosthetic group

Prosthetic group

A prosthetic group is a non-protein component of a conjugated protein that is required for the protein's biological activity. The prosthetic group may be organic compound or inorganic ....
in the center around which the remaining apoprotein

Apoprotein

Apoprotein can refer to:*Apoenzyme, the protein part of an enzyme without its characteristic prosthetic group.*Apolipoprotein, a lipid-binding protein that is a constituent of the plasma lipoprotein....
folds. It has eight alpha helices and a hydrophobic core. It has a molecular weight of 16,700 daltons

Atomic mass unit

The unified atomic mass unit , or dalton or, sometimes, universal mass unit, is a Units of measurement of mass used to express atomic weight and molecular masses....
, and is the primary oxygen

Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
-carrying pigment

Pigment

A pigment is a material that changes the color of light it Reflection as the result of selective color absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which the material itself emits light....
of muscle

MUSCLE

MUSCLE is public domain, multiple sequence alignment software for protein and nucleotide sequences.MUSCLE is integrated into UGENE bioinformatics tool as a plugin....
tissues. Unlike the blood-borne hemoglobin

Hemoglobin

Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of vertebrates, and the tissues of some invertebrates....
, to which it is structurally related, this protein does not exhibit cooperative binding

Cooperative binding

In biochemistry, a macromolecule exhibits cooperative binding if its affinity for its ligand changes with the amount of ligand already bound....
of oxygen, since positive cooperativity is a property of multimeric/oligomeric

Oligomer

In chemistry, an oligomer consists of a limited number of monomer units , in contrast to a polymer which, at least in principle, consists of an unbounded number of monomers....
proteins only.

Discussion

Ask a question about 'Myoglobin'

Start a new discussion about 'Myoglobin'

Answer questions from other users

Full Discussion Forum

Encyclopedia

Myoglobin is a single-chain

Tertiary structure

In biochemistry and chemistry, the tertiary structure of a protein or any other macromolecule is its three-dimensional structure, as defined by the atomic coordinates....
globular protein

Protein

Amino acid

Heme

A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin....
(iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. Iron is a Group 8 element and period 4 element. Iron is lustrous and silvery in color....
-containing porphyrin

Porphyrin

Porphyrins are a group of chemical compounds of which many occur in nature, such as in green leaves and red blood cells, and in bio-inspired synthetic catalysts and devices....
) prosthetic group

Prosthetic group

Apoprotein

Atomic mass unit

Oxygen

Pigment

MUSCLE

Hemoglobin

Cooperative binding

Oligomer

In chemistry, an oligomer consists of a limited number of monomer units , in contrast to a polymer which, at least in principle, consists of an unbounded number of monomers....
proteins only. 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

Dissociation (chemistry)

Dissociation in chemistry and biochemistry is a general process in which ionic compounds separate or split into smaller molecules, ions, or Radical , usually in a reversible manner....
curve. High concentrations of myoglobin in muscle cells allow organisms to hold their breaths longer. In 1958, John Kendrew

John Kendrew

Sir John Cowdery Kendrew, Commander of the Order of the British Empire, Fellow of the Royal Society was an England biochemist and crystallography who shared the 1962 Nobel Prize in Chemistry with Max Perutz; their group in the Cavendish Laboratory investigated the structure of heme-containing proteins....
and associates successfully determined the structure of myoglobin by high-resolution X-ray crystallography

X-ray crystallography

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 into many different directions....
. For this discovery, John Kendrew shared the 1962 Nobel Prize in chemistry

Nobel Prize in Chemistry

The Nobel Prize in Chemistry is awarded annually by the Royal Swedish Academy of Sciences to scientists in the various fields of chemistry. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895, awarded for outstanding contributions in chemistry, Nobel Prize in Physics, Nobel Prize in Literature, Nobel Peace Pri...
with Max Perutz

Max Perutz

Max Ferdinand Perutz, Order of Merit was an Austrian-United Kingdom molecular biologist, who was awarded the Nobel Prize for Chemistry in 1962, shared with John Kendrew for their studies of the structures of hemoglobin and globular proteins....
. The human version of this gene is MB. 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.

Meat color

$Myoglobindiffraction$

Myoglobin forms pigment

Pigment

Red Meat

Begun in 1989, Max Cannon's Red Meat is an independent comic strip. It appears in over 75 alternative weeklies and college papers in the United States and in other countries....
. 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 is in the +2 oxidation state, and is bound to a dioxygen molecule (O₂). Meat cooked well done is brown because the iron atom is now in the +3 oxidation state. Having lost an electron, and is now coordinated by a water molecule. 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

Nitric oxide

Nitric oxide or nitrogen monoxide is a chemical compound with chemical formula NitrogenOxygen. This gas is an important signaling molecule in the body of mammals, including humans, and is an extremely important intermediate in the chemical industry....
(true of, e.g., corned beef

Corned beef

In the U.S. and Canada, Corned beef has two meanings. One refers to a cut of beef Curing or Pickling in a seasoned brine. The other use of the term refers to a tinned product generally found with canned goods on supermarket shelves ...
or cured ham

Ham

Ham is the thigh and rump of pork, cut from the haunch of a pig or boar. Although it may be cooked and served fresh, most ham is Curing in some fashion....
s). Grilled meats can also take on a pink "smoke ring

Smoke ring

A smoke ring is a visible vortex ring formed by expelling smoke through an opening. It can be created by blowing smoke from the mouth, while smoking....
" that comes from the iron binding a molecule of carbon monoxide to give metmyoglobin

Metmyoglobin

Metmyoglobin is the oxidised form of the oxygen-carrying protein myoglobin.Metmyoglobin is the cause of the characteristic brown colouration of meat that occurs as it ages....
. Raw meat packed in a carbon monoxide atmosphere also shows this same pink "smoke ring" due to the same coordination chemistry. 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. 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. 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

Rhabdomyolysis

Rhabdomyolysis is the rapid breakdown of skeletal muscle tissue due to injury to muscle tissue. The muscle damage may be caused by physical , chemical, or biological factors....
), 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

Acute renal failure

Acute renal failure , also known as acute kidney failure or acute kidney injury, is a rapid loss of renal function due to damage to the kidneys, resulting in retention of nitrogenous and non-nitrogenous waste products that are normally excreted by the kidney....
.

Myoglobin is a sensitive marker for muscle injury, making it a potential marker for heart attack

Myocardial infarction

Myocardial infarction , commonly known as a heart attack, occurs when the Blood flow to part of the heart is interrupted. This is most commonly due to occlusion of a coronary artery following the rupture of a Vulnerable plaque, which is an unstable collection of lipids and white blood cells in the wall of an artery....
in patients with chest pain

Chest pain

In medicine, chest pain is a symptom of a number of serious conditions and is generally considered a medical emergency. Even though it may be determined that the chest pain is non-cardiac in origin this is often a diagnosis of exclusion made after ruling out more serious causes of pain....
. CK-MB

Creatine kinase

Creatine kinase , also known as creatine phosphokinase or phosphocreatine kinase, is an enzyme expressed by various tissue types....
and cTnT

Troponin

Troponin is a complex of three regulatory proteins that is integral to muscle contraction in skeletal muscle and cardiac muscle, but not smooth muscle....
is used in combination with ECG

Electrocardiogram

An electrocardiogram is a recording of the electricity activity of the heart over time produced by an electrocardiograph, usually in a Non-invasive recording via skin electrodes....
, and the clinical signs to diagnose Acute Myocardial Infarction (AMI)

Myocardial infarction

Structure and bonding

Myoglobin contains a porphyrin

Porphyrin

Porphyrins are a group of chemical compounds of which many occur in nature, such as in green leaves and red blood cells, and in bio-inspired synthetic catalysts and devices....
ring with an iron center. There is a proximal histidine
Histidine

Histidine is one of the 20 standard amino acids present in proteins. In the nutritional sense, in humans, histidine is considered an essential amino acid, but only in children....
group attached directly to the iron center, and a distal histidine group on the opposite face, not bonded to the iron.

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

Prosthetic group

To form hydrogen bond
Hydrogen bond

A hydrogen bond is the attractive force between one electronegative atom and a hydrogen covalently bonded to another electronegative atom. It results from a dipole-dipole force with a hydrogen atom bonded to nitrogen, oxygen or fluorine ....
s with the dioxygen moiety
Moiety

Moiety may mean:*A part or half of a molecule *In anthropology, a type of descent group*An Australian Aboriginal kinship*Native Hawaiian realm ruled by a Mo'i or Ali'i...
, increasing the O₂ binding constant
To prevent the binding of carbon monoxide
Carbon monoxide

Carbon monoxide, with the chemical formula CO, is a colorless and odorless, tasteless, yet highly toxic gas. Its molecules consist of one carbon atom covalent bond to one oxygen atom....
, whether from within or without the body. Carbon monoxide binds to iron in an end-on fashion, and is hindered by the presence of the distal histidine
Histidine

Histidine is one of the 20 standard amino acids present in proteins. In the nutritional sense, in humans, histidine is considered an essential amino acid, but only in children....
, which forces it into a bent conformation. CO binds to heme 23,000 times better than O₂, but only 200 times better in hemoglobin
Hemoglobin

Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of vertebrates, and the tissues of some invertebrates....
and myoglobin. Oxygen binds in a bent fashion, which can fit with the distal histidine.
To prevent irreversible dimer
Dimer

File:Carboxylic acid dimers.pngA dimer is a chemical or biological entity consisting of two identical subunits called monomers, which are held together by either intramolecular forces or weaker intermolecular forces....
ization of the oxymyoglobin with another deoxymyoglobin species

External links

human genetics
New York Times, February 21, 2006 article regarding meat industry use of carbon monoxide to keep meat looking red.
New York Times, March 1, 2006 article on the use of carbon monoxide to make meat appear fresh.

Myoglobin

Meat color

Role in disease

Structure and bonding

See also

Further reading

External links