Polymorphisms in Factor X have been associated with an increased prevalence in bacterial infections, suggesting a possible role directly regulating the immune response to bacterial pathogens. Therapeutic use
Factor X is part of fresh frozen plasma and the prothrombinase complex. There are two commercially available Factor X concentrates: "Factor X P Behring" manufactured by CSL Behring, and high purity Factor X Coagadex produced by Bio Products Laboratory and approved for use in the United States by the FDA in October 2015, and in the EU in March 2016, after earlier acceptance by CHMP and COMP.Kcentra, manufactured by CSL Behring, is a concentrate containing coagulation Factors II, VII, IX and X, and antithrombotic Proteins C and S.

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 the sequence Ile-Glu/Asp-Gly-Arg, IEGR or IDGR) 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 X, also known as thrombokinase and known eponymously as Stuart-Prower factor. Factor X is an enzyme, a serine endopeptidase, which plays a key role at several stages of the coagulation system. Factor X is synthesized in the liver.
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, darexaban (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. 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). At that time, those investigators could not know that the human genetic defect they had identified would be found in the previously characterized enzyme called thrombokinase. Thrombokinase was the name coined by Paul Morawitz in 1904 to describe the substance that converted prothrombin to thrombin and caused blood to clot. That name embodied an important new concept in understanding blood coagulation – that an enzyme was critically important in the activation of prothrombin.