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A specialist may request a quantitative factor Xa assay in a situation of overdose. [2] Andexanet alfa, a specific antidote to reverse the anticoagulant activity of direct Xa inhibitors in the event of major bleeding, was approved by the FDA in 2018. [9] It is also available in the UK. [10]
The first crystal structure of human factor Xa was deposited in May 1993. To date, 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 subpockets as S1, S2, S3 and S4. The S1 subpocket determines the major component of selectivity and binding.
Results are given in units/mL of anti-factor Xa, such that high values indicate high levels of anticoagulation and low values indicate low levels of anticoagulation in the plasma sample. [ 17 ] LMWHs have a targeted therapeutic window of approximately 0.6–1.2 IU/ml. LMWH has a potency of 70 units/mg of anti-factor Xa activity and a ratio of ...
Factor Xa was identified as a promising target for the development of new anticoagulants in the early 1980s. In 1987 the first factor Xa inhibitor, the naturally occurring compound antistasin, was isolated from the salivary glands of the Mexican leech Haementeria officinalis. Antistasin is a polypeptide and a potent Xa inhibitor.
This study reports results on 352 people and demonstrates a reduction of anti-Xa-activity while also showing an excellent or good hemostatic efficacy in 82%. While people who were expected to die in 30 days were excluded from the study, 14% of participants died. There was no relationship between hemostatic efficacy and reduced anti-Xa-activity ...
The formation of draculin-factor Xa is a two-stage process. The first reversible stage is characterized by the following constants: k1 = 1.117*106 M-1*sec-1, k-1 = 15.388*10-1 sec-1. The second irreversible (concentration-independent) stage is characterized by the forward reaction rate constant k2 = 0.072 sec-1.
Antithrombin (AT) is a small glycoprotein that inactivates several enzymes of the coagulation system. It is a 464-amino-acid protein produced by the liver.It contains three disulfide bonds and a total of four possible glycosylation sites. α-Antithrombin is the dominant form of antithrombin found in blood plasma and has an oligosaccharide occupying each of its four glycosylation sites.
Both factor Xa and factor Va associate with the membrane via their light chains, with factor Xa binding via its Gla-domain in a calcium-dependent manner and factor Va via its C2 and C1 domains. [11] [12] Once bound to the plasma membrane, Factor Xa and factor Va rapidly associate in a 1:1 stoichiometric ratio to form the prothrombinase complex ...