人凝血因子X

Factor X, human

cat#527

Description

Factor X is a vitamin K dependent, two-chain glycoprotein zymogen (Mr = 59,000) synthesized in the liver that circulates in plasma at a concentration of approximately 10 μg/mL. The NH2-terminal light chain (Mr = 17,000) possesses the gammacarboxyglutamic (gla) residues that enable factor X/Xa to bind to phospholipids/membranes in a calcium dependent manner. The COOH-terminal heavy chain (Mr = 42,000) possesses the latent catalytic domain.Activation to factor Xa occurs by interaction with the intrinsic factor Xase complex (Factor VIIa/IXa/Ca+2/phospholipid) or the extrinsic factor Xase complex (Factor VIIa/tissue factor/

Ca+2/phospholipid). Both complexes cleave the molecule at Arg52-lle53, releasing an activation peptide from the heavy chain,resulting in factor Xa as a two-chain molecule where the light chain remains with a Mr of 17,000 and the heavy chain has been reduced to a Mr of 29,000.Factor Xa provides the enzymatic activity of the Prothrombinase complex (Factor Xa/Factor Va/ Ca+2/phospholipid) which converts prothrombin to thrombin. While factor Xa can convert prothrombin to thrombin alone, its activity is greatly enhanced when a part of

the complex. Its activity may be inhibited by inactivation of the factor Va cofactor or directly by a natural inhibitor such as antithrombin III.

Preparation

Human factor X is purified from human plasma via a combination of barium citrate adsorption, ammonium sulphate fractionation,ion-exchange and immunoaffinity chromatography.

Presentation

Screw-capped glass vial containing 80 μg of human factor X lyophilized from a 160 μL solution of 20 mM Tris, 100 mM NaCl,0.3 mg/mL BSA and 100 mM mannitol, pH 7.3. Protein content was determined by spectrophotometric analysis at a wavelength of 280 nm using an extinction coefficient of 1.16 for a 0.1%

solution, 1 cm pathlength.

Reconstitution

Add 80 μL of filtered deionized or sterile water to generate a 1.0 mg/mL stock solution.

Storage

Store the lyophilized protein at 2°-8°C. Aliquot and store reconstituted protein at –20°C or colder.