Factor Xa, Gla-domainless, Human, Highly Purified

Participation of Factor Xa in Prothrombinase: Membrane bound factor Xa binds to membrane bound factor Va to form the prothrombinase complex. This complex effectively converts the zymogen prothrombin (II) to the active serine protease thrombin (IIa) by proteolytic removal of the fragment 1.2 (F1.2) portion of prothrombin. ,  , Activation of the zymogen, factor X, by either the intrinsic or extrinsic factor Xase complexes produces the active serine protease factor Xa (1,2). The activation of factor X requires proteolytic cleavage of the heavy chain, resulting in the release of an activation glycopeptide. The heavy chain region in factor Xa contains the serine protease catalytic domain, while the light chain, as in the zymogen, contains the membrane binding domain. Factor Xa participates in the prothrombinase complex, which catalyzes the rapid conversion of prothrombin to thrombin. Prothrombinase is an enzyme complex composed of factor Xa (enzyme) and factor Va (cofactor) assembled on a cellular surface in the presence of calcium ions. Although factor Xa can independently catalyze the activation of prothrombin, the rate at which this reaction occurs is increased nearly 300,000-fold with complete assembly of the prothrombinase complex. The clotting activity of factor Xa in vivo is terminated by either inactivation of the cofactor, factor Va, or by direct inhibition of factor Xa by inhibitors, such as ATIII, after disassembly of the prothrombinase complex. , In recent years, molecular biologists have utilized factor Xa for site specific cleavage of fusion proteins expressed in bacteria (9-12). A factor Xa-sensitive site is incorporated between the recombinant protein of interest and peptides or proteins which facilitate purification and/or expression. The target protein is released from the expressed hybrid by cleavage with factor Xa. The factor Xa can then be easily removed by affinity chromatography. Storage and Stability: May be stored at 4°C for short-term only. For long-term storage, store at -20°C. Aliquots are stable for at least 6 months at -20°C. 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. , Additional Specifications:, Localization: Plasma , Mode of Action: Enzyme component of the prothrombinase complex , Extinction Coefficient: E1%1cm, 280nm=11.6 (6), Specific Activity: ~1000 units/mg , Structure: One subunit, Mr=29,000 (6), two EGF domains., , Percent carbohydrate: 3.0% (8)