Factor X is a vitamin K-dependent protein zymogen which is synthesized in the liver and circulates in plasma as a two chain molecule linked by a disulfide bond (1,2). Prior to secretion into plasma, post-translational modifications produce 11 gamma-carboxyglutamic acid (gla) residues and a single b-hydroxyaspartic acid residue, which are located within the NH2-terminal light chain. The light chain also contains two epidermal growth factor (EGF) homology domains. The COOH-terminal heavy chain of factor X contains most of the carbohydrate moieties, as well as the latent serine protease domain. The activation of factor X is catalyzed by either the intrinsic factor Xase complex (factor IXa, factor VIIIa, cellular surface and calcium ions) or the extrinsic factor Xase complex (factor VIIa, tissue factor, cellular surface and calcium ions). Activation of human factor X by either complex results in cleavage at Arg52-Ile53 of the COOH-terminal heavy chain and subsequent release of a 52 amino acid activation glycopeptide. Factor Xa then serves as the enzyme component of the prothrombinase complex which is responsible for the rapid conversion of prothrombin to thrombin. The gla residues enable factor X/Xa to bind phospholipid (i.e. cell surfaces) in a calcium dependent manner, a requirement for assembly of the prothrombinase complex. The first EGF homology domain contains a Ca+2 binding site which acts as a hinge to fold the EGF and GLA domains towards each other (12). This region of the molecule is involved in the recognition of cellular binding domains. Mode of Action: Zymogen, precursor to the serine protease factor Xa Extinction Coefficient: E1%1cm, 280nm= 9.8 Structure: Two subunits, Mr=16,200 and 42,000, and two EGF domains Isoelectric Point: 4.9-5.2 Percent Carbohydrate: 15% Specific Activity: < 2% X activity. Determined by Factor X clotting assay. One unit is equivalent to the Factor X activity in one milliliter of normal plasma. Storage and Stability: May be stored at 4C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20C. Aliquots are stable for 6 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
Molekulargewicht:
50900
Reinheit:
95%. Human factor X is isolated from fresh frozen human plasma by a combination of conventional techniques and immunoaffinity chromatography. Purity is determined by SDS-PAGE analysis.
Formulierung:
Supplied as a liquid in 50% glycerol/H2O.
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