Factor X
Encyclopedia
Factor X, also known by the eponym
Stuart-Prower factor or as prothrombinase, is an enzyme
of the coagulation cascade
. It is a serine endopeptidase
(protease group S1).
and requires vitamin K
for its synthesis.
Factor X is activated into factor Xa by both factor IX
(with its cofactor, factor VIII
in a complex known as intrinsic Xase) and factor VII
with its cofactor, tissue factor
(a complex known as extrinsic Xase). It is therefore the first member of the final common pathway or thrombin pathway.
It acts by cleaving prothrombin in two places (an arg
-thr
and then an arg
-ile
bond), which yields the active thrombin
. This process is optimized when factor Xa is complexed with activated co-factor V
in the prothrombinase
complex.
Factor Xa is inactivated by protein Z-dependent protease inhibitor (ZPI), a serine protease inhibitor (serpin). The affinity of this protein for factor Xa is increased 1000-fold by the presence of protein Z
, while it does not require protein Z for inactivation of factor XI
. Defects in protein Z lead to increased factor Xa activity and a propensity for thrombosis.
The half life of factor X is 40-45 hours.
(bleeding into joints) and gastrointestinal blood loss. Apart from congenital deficiency, low factor X levels may occur occasionally in a number of disease states. For example, factor X deficiency may be seen in amyloidosis
, where factor X is adsorbed to the amyloid fibrils in the vasculature.
Deficiency of vitamin K or antagonism by warfarin
(or similar medication) leads to the production of an inactive factor X. In warfarin therapy, this is desirable to prevent thrombosis
. As of late 2007, four out of five emerging anti-coagulation
therapeutics targeted this enzyme.
Inhibiting Factor Xa would offer an alternate method for anticoagulation. Direct Xa inhibitors are popular anticoagulants.
and the prothrombinase complex. The only commercially available concentrate is 'Factor X P Behring' manufactured by CSL Behring
.
, a serine endopeptidase, which plays a key role at several stages of the coagulation system. Factor X is synthesized
in the liver
. The most commonly used anticoagulants in clinical practice, warfarin
and the heparin
series of anticoagulants and fondaparinux
, act to inhibit the action of Factor Xa in various degrees.
Traditional models of coagulation developed in the 1960’s envisaged two separate cascades, the extrinsic (tissue factor (TF))
pathway and the intrinsic pathway. These pathways converge to a common point, the formation of the Factor Xa/Va complex which together with calcium
and bound on a phospholipids surface generate thrombin (Factor IIa)
from prothrombin (Factor II).
A new model, the cell-based model of anticoagulation appears to explain more fully the steps in coagulation. This model has three stages: 1) initiation of coagulation on TF-bearing cells, 2) amplification of the procoagulant signal by thrombin generated on the TF-bearing cell and 3) propagation of thrombin generation on the platelet
surface. Factor Xa plays a key role in all three of these stages.
In stage 1, Factor VII
binds to the transmembrane protein
TF on the surface of cells and is converted to Factor VIIa. The result is a Factor VIIa/TF complex which catalyzes the activation of Factor X and Factor IX
. Factor Xa formed on the surface of the TF-bearing cell interacts with Factor V
a to form the prothrombinase complex
which generates small amounts of thrombin on the surface of TF-bearing cells.
In stage 2, the amplification stage, if enough thrombin has been generated, then activation of platelets and platelet associated cofactors
occurs.
In stage 3, thrombin generation, Factor XI
a activates free Factor IX on the surface of activated platelets. The activated Factor IXa with Factor VIII
a forms the ”tenase” complex
. This “tenase” complex activates more Factor X, which in turn forms new prothrombinase complexes with Factor Va. Factor Xa is the prime component of the prothrombinase complex which converts large amounts of prothrombin – the “thrombin burst”. Each molecule of Factor Xa can generate 1000 molecules of thrombin. This large burst of thrombin is responsible for fibrin
polymerization
to form a thrombus
.
Inhibition of the synthesis or activity of Factor X is the mechanism of action for many anticoagulants in use today. Warfarin, a synthetic derivative of coumarin
, is the most widely used oral anticoagulant in the US. In some European countries, other coumarin derivatives (phenprocoumon
and acenocoumarol
) are used. These agents are vitamin K antagonists (VKA)
. Vitamin K is essential for the hepatic synthesis of Factors II (prothrombin), VII, IX and X.
Heparin (unfractionated heparin) and its derivatives low molecular weight heparin (LMWH)
bind to a plasma
cofactor, antithrombin (AT)
to inactivate several coagulation factors IIa, Xa, XIa and XIIa. The affinity of unfractionated heparin and the various LMWHs for Factor Xa varies considerably. The efficacy of heparin-based anticoagulants increases as selectivity for Factor Xa increases. LMWH shows increased inactivation of Factor Xa compared to unfractionated heparin, and fondaparinux, an agent based on the critical pentasacharide sequence of heparin, shows more selectivity than LMWH. This inactivation of Factor Xa by heparins is termed “indirect” since it relies on the presence of AT and not a direct interaction with Factor Xa.
Recently a new series of specific, direct acting inhibitors of Factor Xa has been developed. These include the drugs rivaroxaban
, apixaban
, betrixaban
, LY517717, YM150, edoxaban
and 813893. These agents have several theoretical advantages over current therapy. They may be given orally. They have rapid Onset of action. And they may be more effective against Factor Xa in that they inhibit both free Factor Xa and Factor Xa in the prothrombinase complex.
with Tissue factor pathway inhibitor
.
Eponym
An eponym is the name of a person or thing, whether real or fictitious, after which a particular place, tribe, era, discovery, or other item is named or thought to be named...
Stuart-Prower factor or as prothrombinase, is an enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
of the coagulation cascade
Coagulation
Coagulation is a complex process by which blood forms clots. It is an important part of hemostasis, the cessation of blood loss from a damaged vessel, wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel...
. It is a serine endopeptidase
Serine protease
Serine proteases are enzymes that cleave peptide bonds in proteins, in which serine serves as the nucleophilic amino acid at the active site.They are found ubiquitously in both eukaryotes and prokaryotes...
(protease group S1).
Physiology
Factor X is synthesized in the liverLiver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
and requires vitamin K
Vitamin K
Vitamin K is a group of structurally similar, fat soluble vitamins that are needed for the posttranslational modification of certain proteins required for blood coagulation and in metabolic pathways in bone and other tissue. They are 2-methyl-1,4-naphthoquinone derivatives...
for its synthesis.
Factor X is activated into factor Xa by both factor IX
Factor IX
Factor IX is one of the serine proteases of the coagulation system; it belongs to peptidase family S1. Deficiency of this protein causes hemophilia B. It was discovered in 1952 after a young boy named Stephen Christmas was found to be lacking this exact factor, leading to...
(with its cofactor, factor VIII
Factor VIII
Factor VIII is an essential blood clotting factor also known as anti-hemophilic factor . In humans, Factor VIII is encoded by the F8 gene...
in a complex known as intrinsic Xase) and factor VII
Factor VII
Factor VII is one of the proteins that causes blood to clot in the coagulation cascade. It is an enzyme of the serine protease class. A recombinant form of human factor VIIa has U.S. Food and Drug Administration approval for uncontrolled bleeding in hemophilia patients...
with its cofactor, tissue factor
Tissue factor
Tissue factor, also called platelet tissue factor, factor III, thrombokinase, or CD142 is a protein present in subendothelial tissue, platelets, and leukocytes necessary for the initiation of thrombin formation from the zymogen prothrombin. An incorrect synonym is thromboplastin...
(a complex known as extrinsic Xase). It is therefore the first member of the final common pathway or thrombin pathway.
It acts by cleaving prothrombin in two places (an arg
Arginine
Arginine is an α-amino acid. The L-form is one of the 20 most common natural amino acids. At the level of molecular genetics, in the structure of the messenger ribonucleic acid mRNA, CGU, CGC, CGA, CGG, AGA, and AGG, are the triplets of nucleotide bases or codons that codify for arginine during...
-thr
Threonine
Threonine is an α-amino acid with the chemical formula HO2CCHCHCH3. Its codons are ACU, ACA, ACC, and ACG. This essential amino acid is classified as polar...
and then an arg
Arginine
Arginine is an α-amino acid. The L-form is one of the 20 most common natural amino acids. At the level of molecular genetics, in the structure of the messenger ribonucleic acid mRNA, CGU, CGC, CGA, CGG, AGA, and AGG, are the triplets of nucleotide bases or codons that codify for arginine during...
-ile
Isoleucine
Isoleucine is an α-amino acid with the chemical formula HO2CCHCHCH2CH3. It is an essential amino acid, which means that humans cannot synthesize it, so it must be ingested. Its codons are AUU, AUC and AUA....
bond), which yields the active thrombin
Thrombin
Thrombin is a "trypsin-like" serine protease protein that in humans is encoded by the F2 gene. Prothrombin is proteolytically cleaved to form thrombin in the first step of the coagulation cascade, which ultimately results in the stemming of blood loss...
. This process is optimized when factor Xa is complexed with activated co-factor V
Factor V
Factor V is a protein of the coagulation system, rarely referred to as proaccelerin or labile factor. In contrast to most other coagulation factors, it is not enzymatically active but functions as a cofactor...
in the prothrombinase
Prothrombinase
The prothrombinase complex consists of the serine protease, Factor Xa, and the protein cofactor, Factor Va. The complex assembles on negatively charged phospholipid membranes in the presence of calcium ions. The prothrombinase complex catalyzes the conversion of prothrombin , an inactive zymogen,...
complex.
Factor Xa is inactivated by protein Z-dependent protease inhibitor (ZPI), a serine protease inhibitor (serpin). The affinity of this protein for factor Xa is increased 1000-fold by the presence of protein Z
Protein Z
Protein Z also known as PROZ is a protein which in humans is encoded by the PROZ gene.Protein Z is a member of the coagulation cascade, the group of blood proteins that leads to the formation of blood clots. It is vitamin K-dependent, and its functionality is therefore impaired in warfarin therapy...
, while it does not require protein Z for inactivation of factor XI
Factor XI
Factor XI or plasma thromboplastin antecedent is the zymogen form of factor XIa, one of the enzymes of the coagulation cascade. Like many other coagulation factors, it is a serine protease. In humans, Factor XI is encoded by the F11 gene....
. Defects in protein Z lead to increased factor Xa activity and a propensity for thrombosis.
The half life of factor X is 40-45 hours.
Structure of Factor Xa
The first crystal structure of human factor Xa was deposited in May 1993. Till now total 191 crystal structures of factor Xa with various inhibitors have been deposited in the protein data bank. The active site of factor Xa is divided into four sub pockets as S1, S2, S3 and S4. The S1 subpocket determines the major component of selectivity and binding. The S2 sub-pocket is small, shallow and not well defined. It merges with the S4 subpocket. The S3 sub-pocket is located on the rim of the S1 pocket and is quite exposed to solvent. The S4 sub-pocket has 3 ligand binding domains, namely the “hydrophobic box”, the “cationic hole” and the water site. Factor Xa inhibitors generally bind in an L-shaped conformation, where one group of the ligand occupies the anionic S1 pocket lined by residues Asp189, Ser195, and Tyr228, and another group of the ligand occupies the aromatic S4 pocket lined by residues Tyr99, Phe174, and Trp228. Typically, a fairly rigid linker group bridges these two interaction sites.Role in disease
Inborn deficiency of factor X is very uncommon (1:500,000), and may present with epistaxis (nosebleeds), hemarthrosisHemarthrosis
Hemarthrosis is a bleeding into joint spaces.-Causes:It usually follows injury but occurs mainly in patients with a predisposition to hemorrhage such as those being treated with warfarin and patients with hemophilia.It can be associated with knee joint arthroplasty.-Treatment:In hemophilia it may...
(bleeding into joints) and gastrointestinal blood loss. Apart from congenital deficiency, low factor X levels may occur occasionally in a number of disease states. For example, factor X deficiency may be seen in amyloidosis
Amyloidosis
In medicine, amyloidosis refers to a variety of conditions whereby the body produces "bad proteins", denoted as amyloid proteins, which are abnormally deposited in organs and/or tissues and cause harm. A protein is described as being amyloid if, due to an alteration in its secondary structure, it...
, where factor X is adsorbed to the amyloid fibrils in the vasculature.
Deficiency of vitamin K or antagonism by warfarin
Warfarin
Warfarin is an anticoagulant. It is most likely to be the drug popularly referred to as a "blood thinner," yet this is a misnomer, since it does not affect the thickness or viscosity of blood...
(or similar medication) leads to the production of an inactive factor X. In warfarin therapy, this is desirable to prevent thrombosis
Thrombosis
Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...
. As of late 2007, four out of five emerging anti-coagulation
Anticoagulant
An anticoagulant is a substance that prevents coagulation of blood. A group of pharmaceuticals called anticoagulants can be used in vivo as a medication for thrombotic disorders. Some anticoagulants are used in medical equipment, such as test tubes, blood transfusion bags, and renal dialysis...
therapeutics targeted this enzyme.
Inhibiting Factor Xa would offer an alternate method for anticoagulation. Direct Xa inhibitors are popular anticoagulants.
Therapeutic use
Factor X is part of fresh frozen plasmaFresh frozen plasma
The term fresh frozen plasma refers to the liquid portion of human blood that has been frozen and preserved after a blood donation and will be used for blood transfusion...
and the prothrombinase complex. The only commercially available concentrate is 'Factor X P Behring' manufactured by CSL Behring
CSL Behring
CSL Behring is one of the world's leading plasma protein biotherapeutics companies, specializing in the manufacture of therapies for the treatment of rare and serious diseases...
.
Use in Biochemistry
The Factor Xa protease can be used in biochemistry to cleave off protein tags that improve expression or purification of a protein of interest. Its preferred cleavage site (after the arginine in ile-glu/asp-gly-arg) can easily be engineered between a tag sequence and the protein of interest. After expression and purification, the tag is then proteolytically removed by Factor Xa.Factor Xa
Factor Xa is the activated form of the coagulation factor thrombokinase, known eponymously as Stuart-Prower factor. Factor X is an enzymeEnzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
, a serine endopeptidase, which plays a key role at several stages of the coagulation system. Factor X is synthesized
Biosynthesis
Biosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...
in the liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
. The most commonly used anticoagulants in clinical practice, warfarin
Warfarin
Warfarin is an anticoagulant. It is most likely to be the drug popularly referred to as a "blood thinner," yet this is a misnomer, since it does not affect the thickness or viscosity of blood...
and the heparin
Heparin
Heparin , also known as unfractionated heparin, a highly sulfated glycosaminoglycan, is widely used as an injectable anticoagulant, and has the highest negative charge density of any known biological molecule...
series of anticoagulants and fondaparinux
Fondaparinux
Fondaparinux is an anticoagulant medication chemically related to low molecular weight heparins. It is marketed by GlaxoSmithKline.-Structure and mechanism:Fondaparinux is a synthetic pentasaccharide Factor Xa inhibitor...
, act to inhibit the action of Factor Xa in various degrees.
Traditional models of coagulation developed in the 1960’s envisaged two separate cascades, the extrinsic (tissue factor (TF))
Tissue factor
Tissue factor, also called platelet tissue factor, factor III, thrombokinase, or CD142 is a protein present in subendothelial tissue, platelets, and leukocytes necessary for the initiation of thrombin formation from the zymogen prothrombin. An incorrect synonym is thromboplastin...
pathway and the intrinsic pathway. These pathways converge to a common point, the formation of the Factor Xa/Va complex which together with calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
and bound on a phospholipids surface generate thrombin (Factor IIa)
Thrombin
Thrombin is a "trypsin-like" serine protease protein that in humans is encoded by the F2 gene. Prothrombin is proteolytically cleaved to form thrombin in the first step of the coagulation cascade, which ultimately results in the stemming of blood loss...
from prothrombin (Factor II).
A new model, the cell-based model of anticoagulation appears to explain more fully the steps in coagulation. This model has three stages: 1) initiation of coagulation on TF-bearing cells, 2) amplification of the procoagulant signal by thrombin generated on the TF-bearing cell and 3) propagation of thrombin generation on the platelet
Platelet
Platelets, or thrombocytes , are small,irregularly shaped clear cell fragments , 2–3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes. The average lifespan of a platelet is normally just 5 to 9 days...
surface. Factor Xa plays a key role in all three of these stages.
In stage 1, Factor VII
Factor VII
Factor VII is one of the proteins that causes blood to clot in the coagulation cascade. It is an enzyme of the serine protease class. A recombinant form of human factor VIIa has U.S. Food and Drug Administration approval for uncontrolled bleeding in hemophilia patients...
binds to the transmembrane protein
Transmembrane protein
A transmembrane protein is a protein that goes from one side of a membrane through to the other side of the membrane. Many TPs function as gateways or "loading docks" to deny or permit the transport of specific substances across the biological membrane, to get into the cell, or out of the cell as...
TF on the surface of cells and is converted to Factor VIIa. The result is a Factor VIIa/TF complex which catalyzes the activation of Factor X and Factor IX
Factor IX
Factor IX is one of the serine proteases of the coagulation system; it belongs to peptidase family S1. Deficiency of this protein causes hemophilia B. It was discovered in 1952 after a young boy named Stephen Christmas was found to be lacking this exact factor, leading to...
. Factor Xa formed on the surface of the TF-bearing cell interacts with Factor V
Factor V
Factor V is a protein of the coagulation system, rarely referred to as proaccelerin or labile factor. In contrast to most other coagulation factors, it is not enzymatically active but functions as a cofactor...
a to form the prothrombinase complex
Prothrombinase
The prothrombinase complex consists of the serine protease, Factor Xa, and the protein cofactor, Factor Va. The complex assembles on negatively charged phospholipid membranes in the presence of calcium ions. The prothrombinase complex catalyzes the conversion of prothrombin , an inactive zymogen,...
which generates small amounts of thrombin on the surface of TF-bearing cells.
In stage 2, the amplification stage, if enough thrombin has been generated, then activation of platelets and platelet associated cofactors
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....
occurs.
In stage 3, thrombin generation, Factor XI
Factor XI
Factor XI or plasma thromboplastin antecedent is the zymogen form of factor XIa, one of the enzymes of the coagulation cascade. Like many other coagulation factors, it is a serine protease. In humans, Factor XI is encoded by the F11 gene....
a activates free Factor IX on the surface of activated platelets. The activated Factor IXa with Factor VIII
Factor VIII
Factor VIII is an essential blood clotting factor also known as anti-hemophilic factor . In humans, Factor VIII is encoded by the F8 gene...
a forms the ”tenase” complex
Tenase
In coagulation, the procoagulant protein factor X can be activated into factor Xa two ways. Extrinsic and intrinsic ways.The activating complexes are called tenase...
. This “tenase” complex activates more Factor X, which in turn forms new prothrombinase complexes with Factor Va. Factor Xa is the prime component of the prothrombinase complex which converts large amounts of prothrombin – the “thrombin burst”. Each molecule of Factor Xa can generate 1000 molecules of thrombin. This large burst of thrombin is responsible for fibrin
Fibrin
Fibrin is a fibrous, non-globular protein involved in the clotting of blood. It is a fibrillar protein that is polymerised to form a "mesh" that forms a hemostatic plug or clot over a wound site....
polymerization
Polymerization
In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...
to form a thrombus
Thrombus
A thrombus , or blood clot, is the final product of the blood coagulation step in hemostasis. It is achieved via the aggregation of platelets that form a platelet plug, and the activation of the humoral coagulation system...
.
Inhibition of the synthesis or activity of Factor X is the mechanism of action for many anticoagulants in use today. Warfarin, a synthetic derivative of coumarin
Coumarin
Coumarin is a fragrant chemical compound in the benzopyrone chemical class, found in many plants, notably in high concentration in the tonka bean , vanilla grass , sweet woodruff , mullein , sweet grass , cassia cinnamon and sweet clover...
, is the most widely used oral anticoagulant in the US. In some European countries, other coumarin derivatives (phenprocoumon
Phenprocoumon
Phenprocoumon is an anticoagulant drug, a derivative of coumarin. It is a vitamin K antagonist that inhibits coagulation by blocking synthesis of coagulation factors II, VII, IX and X...
and acenocoumarol
Acenocoumarol
Acenocoumarol is an anticoagulant that functions as a vitamin K antagonist . It is a derivative of coumarin and is marketed under the brand names Sintrom and Sinthrome.- Dosage :...
) are used. These agents are vitamin K antagonists (VKA)
Vitamin K
Vitamin K is a group of structurally similar, fat soluble vitamins that are needed for the posttranslational modification of certain proteins required for blood coagulation and in metabolic pathways in bone and other tissue. They are 2-methyl-1,4-naphthoquinone derivatives...
. Vitamin K is essential for the hepatic synthesis of Factors II (prothrombin), VII, IX and X.
Heparin (unfractionated heparin) and its derivatives low molecular weight heparin (LMWH)
Low molecular weight heparin
In medicine, low-molecular-weight heparin is a class of medication used as an anticoagulant in diseases that feature thrombosis, as well as for prophylaxis in situations that lead to a high risk of thrombosis....
bind to a plasma
Blood plasma
Blood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...
cofactor, antithrombin (AT)
Antithrombin
Antithrombin is a small protein molecule that inactivates several enzymes of the coagulation system. Antithrombin is a glycoprotein produced by the liver and consists of 432 amino acids. It contains three disulfide bonds and a total of four possible glycosylation sites...
to inactivate several coagulation factors IIa, Xa, XIa and XIIa. The affinity of unfractionated heparin and the various LMWHs for Factor Xa varies considerably. The efficacy of heparin-based anticoagulants increases as selectivity for Factor Xa increases. LMWH shows increased inactivation of Factor Xa compared to unfractionated heparin, and fondaparinux, an agent based on the critical pentasacharide sequence of heparin, shows more selectivity than LMWH. This inactivation of Factor Xa by heparins is termed “indirect” since it relies on the presence of AT and not a direct interaction with Factor Xa.
Recently a new series of specific, direct acting inhibitors of Factor Xa has been developed. These include the drugs rivaroxaban
Rivaroxaban
Rivaroxaban is an oral anticoagulant invented and manufactured by Bayer; in a number of countries it is marketed as Xarelto. In the United States, it is marketed by Janssen Pharmaceutica. It is the first available orally active direct factor Xa inhibitor. Rivaroxaban is well absorbed from the gut...
, apixaban
Apixaban
Apixaban is a compound being investigated as an anticoagulant. It is a direct factor Xa inhibitor. It is presently undergoing phase III trials in the prevention of venous thromboembolism, together with a number of related competing compounds, such as rivaroxaban...
, betrixaban
Betrixaban
Betrixaban is an anticoagulant drug which acts as a direct factor Xa inhibitor. It is potent, orally active and highly selective for factor Xa, being selected from a group of similar compounds for its low hERG affinity...
, LY517717, YM150, edoxaban
Edoxaban
Edoxaban is an anticoagulant drug which acts as a direct factor Xa inhibitor. It is being developed by Daiichi Sankyo...
and 813893. These agents have several theoretical advantages over current therapy. They may be given orally. They have rapid Onset of action. And they may be more effective against Factor Xa in that they inhibit both free Factor Xa and Factor Xa in the prothrombinase complex.
History
American and British scientists described deficiency of factor X independently in 1953 and 1956, respectively. As with some other coagulation factors, the factor was initially named after these patients, a Mr Rufus Stuart (1921) and a Miss Audrey Prower (1934).External links
- The MEROPSMeropsMerops may refer to:* Merops , a genus of bee-eaters.* MEROPS, an on-line database for peptidases.It may also refer to several figures from Greek mythology:* King of Ethiopia, husband of Clymene, who lay with Helios and bore Phaethon...
online database for peptidases and their inhibitors: S01.216 - Factor X deficiency
Interactions
Factor X has been shown to interactProtein-protein interaction
Protein–protein interactions occur when two or more proteins bind together, often to carry out their biological function. Many of the most important molecular processes in the cell such as DNA replication are carried out by large molecular machines that are built from a large number of protein...
with Tissue factor pathway inhibitor
Tissue factor pathway inhibitor
Tissue factor pathway inhibitor is a single-chain polypeptide which can reversibly inhibit Factor Xa and Thrombin...
.