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Factor XIII
 
 
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Factor XIII or fibrin stabilizing factor is an enzyme
Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
  of the blood coagulation system
Coagulation

Coagulation is a complex process by which blood forms clots. It is an important part of hemostasis , wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop hemorrhage and begin repair of the damaged vessel....
 that crosslinks fibrin
Fibrin

Fibrin is a fibrous protein involved in the clotting of blood, and is non globular. It is a fibrillar protein that is Polymerization to form a "mesh" that forms a hemostasis plug or clot over a wound site....
. When thrombin
Thrombin

Thrombin is a coagulation protein that has many effects in the coagulation#The_coagulation_cascade. It is a serine protease that converts soluble fibrinogen into insoluble strands of fibrin, as well as catalyzing many other coagulation-related reactions....
 has converted fibrinogen to fibrin, the latter forms a proteinaceous network in which every E-unit is crosslinked to only one D-unit. Factor XIII is activated by thrombin into factor XIIIa; its activation into Factor XIIIa requires calcium
Calcium in biology

Calcium plays a pivotal role in the physiology and biochemistry of organisms and the cell . It plays an important role in signal transduction pathways, where it acts as a second messenger, in neurotransmitter release from neurons, contraction of all muscle cell types, and fertilization....
 as a cofactor
Cofactor (biochemistry)

A cofactor is a non-protein chemical compound that is bound to an enzyme and is required for catalysis. They can be considered "helper molecules/ions" that assist in biochemical transformations....
.

FXIII is known also as Laki-Lorand factor, after the scientists who first proposed its existence in 1948.






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Factor Xiii


Factor XIII or fibrin stabilizing factor is an enzyme
Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
  of the blood coagulation system
Coagulation

Coagulation is a complex process by which blood forms clots. It is an important part of hemostasis , wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop hemorrhage and begin repair of the damaged vessel....
 that crosslinks fibrin
Fibrin

Fibrin is a fibrous protein involved in the clotting of blood, and is non globular. It is a fibrillar protein that is Polymerization to form a "mesh" that forms a hemostasis plug or clot over a wound site....
. When thrombin
Thrombin

Thrombin is a coagulation protein that has many effects in the coagulation#The_coagulation_cascade. It is a serine protease that converts soluble fibrinogen into insoluble strands of fibrin, as well as catalyzing many other coagulation-related reactions....
 has converted fibrinogen to fibrin, the latter forms a proteinaceous network in which every E-unit is crosslinked to only one D-unit. Factor XIII is activated by thrombin into factor XIIIa; its activation into Factor XIIIa requires calcium
Calcium in biology

Calcium plays a pivotal role in the physiology and biochemistry of organisms and the cell . It plays an important role in signal transduction pathways, where it acts as a second messenger, in neurotransmitter release from neurons, contraction of all muscle cell types, and fertilization....
 as a cofactor
Cofactor (biochemistry)

A cofactor is a non-protein chemical compound that is bound to an enzyme and is required for catalysis. They can be considered "helper molecules/ions" that assist in biochemical transformations....
.

FXIII is known also as Laki-Lorand factor, after the scientists who first proposed its existence in 1948. A 2005 conference recommended standardization of nomenclature.

Genetics

Zymogene factor XIII is a 320000 Mr glycoprotein tetramer consisting of twice two subunits (2 A and 2 B), the gene
Gene

A gene is the basic unit of heredity in a living organism. All living things depend on genes. Genes hold the information to build and maintain their cell and pass genetic trait to offspring....
s for which are on different chromosome
Chromosome

A chromosome is an organized structure of DNA and protein that is found in Cell . A chromosome is a single piece of DNA that contains many genes, regulatory sequence and other genetic sequence....
s:
  • A subunit (6p25-p24). The transglutaminase
    Transglutaminase

    Transglutaminases are a family of enzymes that catalyze the formation of a covalent bond between a free amine group and the gamma-carboxamid group of protein- or peptide-bound glutamine....
     part; this adds an alkyl group to the nitrogen on a glutamine
    Glutamine

    Glutamine is one of the 20 amino acids encoded by the standard genetic code. Its side chain is an amide formed by replacing the side-chain hydroxyl of glutamic acid with an amine functional group....
     residue, which binds in turn with a lysine
    Lysine

    Lysine is an a-amino acid with the chemical formula HO2CCH4NH2. This amino acid is an essential amino acid, which means that humans cannot synthesize it....
     on the other chain. The molecular weight of the A chain is approximately 83000.
  • B subunit (1q31-q32.1). This has no clear enzymatic activity, and may serve as a carrier for the A subunit. The molecular weight of the B chain is approximately 76500.


Physiology

Typical concentrations of FXIII in plasma is 10 µg/ml (2A2B heterodimer), while the concentration of free B chain is 22 µg/ml. FXIII has a long half life, ranging from 5-9 days. It is present in plasma, platelet
Platelet

Platelets, or Thrombocyte, are small, irregularly shaped anuclear cells, 2-4?m in diameter, which are derived from fragmentation of precursor megakaryocytes....
s, and monocyte
Monocyte

Monocyte is a type of leukocyte, part of the human body's immune system. Monocytes have two main functions in the immune system: replenish resident macrophages and dendritic cells under normal states, and in response to inflammation signals, monocytes can move quickly to sites of infection in the tissues and divide/differentiate into mac...
s, as well as macrophage
Macrophage

Macrophages are white blood cells within tissues, produced by the division of monocytes. Human macrophages are about 21 micrometres in diameter....
s and bone marrow precursors of these cell types.

A clot that has not been stabilized by FXIIIa is soluble in 5 mol/L urea
Urea

Urea is an organic compound with the chemical formula 2carbonoxygen.Urea is also known by the International Nonproprietary Name carbamide, as established by the World Health Organization....
, while a stabilized clot is resistant to this phenomenon.

Diagnostic use

Factor XIII levels are not measured routinely, but may be considered in patients with an unexplained bleeding tendency. As the enzyme is quite specific for monocytes and macrophages, determination of the presence of factor XIII may be used to identify and classify malignant diseases involving these cells.

See also

  • Factor XIII deficiency
    Factor XIII deficiency

    Factor XIII deficiency may occur very rarely, and can cause a severe bleeding tendency. Incidence is 1 in a million to 1 in 5 million people. Most are due to mutations in the A subunit....
  • D-dimer
    D-dimer

    D-dimer is a fibrin degradation product, a small protein fragment present in the blood after a thrombus is degraded by fibrinolysis.D-dimer concentration may be determined by a blood test to help diagnose thrombosis....


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