Bovine 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. Prior to secretion into plasma, post-translational modifications produce 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 X-ase complex (factor IXa, factor VIIIa, cellular surface and calcium ions) or the extrinsic factor X-ase complex (factor VIIa, tissue factor, cellular surface and calcium ions). Activation of bovine 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. This region of the molecule is involved in the recognition of cellular binding domains. Specific Activity: 32 Units/mg. One unit is equvialent to the Factor X activity in 1ml of normal plasma. Structure: Two subunits, Mr=16.5kD and 39.3kD NH2-terminal gla domain, and two EGF domains. Isoelectric point: 4.8-5.2 Localization: Plasma Mode of action: Zymogen, precursor to the serine protease factor Xa Extinction Coefficient (1%, 1cm, 280nm): 12.4 Percent Carbohydrate: 10% Post-translational Modifications: Eleven gla residues (7,8), One b-hydroxyaspartate. 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 after receipt 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:
55.1
Reinheit:
95%. Purified using a modification of the procedure reported by Bajaj et al. (5,6). Purity is determined by SDS-PAGE analysis and the activity is measured in a Factor X clotting assay.
Formulierung:
Supplied as a liquid in 50% glycerol, H2O.
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