Factor XII, human
|Antibody||Host||Catalogue No.||Size||Product Insert|
|Purified IgG||Goat||GAFXII-IG||5 mg|
|Affinity purified IgG||Goat||GAFXII-AP||0.5 mg|
|Peroxidase conjugated IgG||Goat||GAFXII-HRP||0.2 mg|
|Matched Pair Antibodies for EIA||FXII-EIA||5 plates|
Description of Factor XII F12
Factor XII (FXII, Hageman factor) is a 76 kDa, single chain glycoprotein produced in the liver. In plasma, FXII circulates as a protease zymogen at a concentration of approximately 30 μg/ml (400 nM). Upon vascular injury FXII binds to negatively charged extravascular surfaces such as cartilage and skin, which facilitate activation of the zymogen to the active serine protease. Cleavage of F.XII by kallikrein after residue Arg353 produces the enzyme αFXIIa, consisting of a 28 kDa light chain containing the protease domain, and a 52 kDa heavy chain containing the anionic surface-binding domain. Substrates for surface bound FXIIa include the zymogens prekallikrein (PK) and factor XI (FXI) as well as the procofactor high-molecular weight kininogen (HK). The activation of these substrates results in positive feedback activation of FXII. Further cleavage of αFXIIa by kallikrein produces the 28 kDa fragment βFXIIa (Hageman factor fragment). βFXIIa has reduced procoagulant activity as it lacks the anionic surface-binding domain, but is capable of fluid-phase activation of PK, factor VII and complement C1. The activity of F.XIIa in plasma is regulated predominantly by C1-Inhibitor, with relatively minor contributions by α2antiplasmin, α2macroglobulin and antithrombin, even in the presence of therapeutic levels of heparin1-3.References and Reviews
- DeLa Cadena R, Watchtfogel YT, Colman RW, in Hemostasis and Thrombosis, 3rd Edition, eds. RW Colman, J Hirsh, VJ Marder and EW Salzman, pp. 219-240, J.B. Lippincott Co., Philadelphia, 1994.
- Tankersley DL, Alving BM, Finlayson JS; Preparation of βF.XIIa (Hageman Factor Fragment) from Human Plasma. Thrombosis Research 25 pp 307-317, 1982.
- Pixley RA, Schapira M, Coleman RW; The regulation of Human Factor XIIa by Plasma Proteinase Inhibitors. JBC 260, pp 1723-1729, 1985.