Factor XI Deficient – Depleted Plasma
Factor XI Deficient – Depleted Plasma is manufactured from normal citrated human plasma that has been depleted of Factor XI by selective affinity immuno-adsorption using antibodies directed towards FXI.
Only the highest quality citrated plasma is used as starting material and in many cases the parent plasma is available as control material. Plasma products are typically buffered with the addition of HEPES to 20mM final concentration and are available in 1ml vials to litre quantities. Our Factor XI Deficient – Depleted Plasma can be used for further manufacturing or research use only applications.
Product Code: FXI-DP
Presentation: Frozen Factor XI Deficient – Depleted Plasma
Preparation/Handling: Thaw 1 ml vials in 37oC water bath for 5 minutes; for bulk volumes, thawing time will be dependent on bottle size.
Storage and Stability: Plasma is shipped frozen and should be stored below -60oC. Product is stable until date stated on vial label when stored at -60oC. Once thawed, plasma is stable for 4 hours at 2-8oC in original vial.
Certificate of Analysis: available upon request
Description of Factor XI (FXI)
Factor XI (FXI, plasma thromboplastin antecedent) is a coagulation protein produced in the liver that circulates in plasma at approximately 5 μg/mL (30 nM). The mass of FXI is 160 kDa as determined by SDS-PAGE under non-reducing conditions and 80 kDa upon reduction. FXI consists of two identical 80 kDa subunits linked by disulphide bonds. Each subunit consists of a tandem repeat of four apple domains followed by a serine protease catalytic domain. Cleavage of FXI by activated factor XII or thrombin converts each subunit into a two-chain form and generates two active sites per FXIa molecule. The mass of FXIa is 160 kDa unreduced, but upon reduction FXIa migrates as a heavy chain of 50 kDa and a light chain of 30 kDa. The catalytic site of FXIa resides in the light chain. In plasma, FXI or FXIa circulates in non-covalent 1:1 complex with high molecular weight kininogen, which acts as a cofactor in the activation of FXI by activated factor XII. The activity of FXIa is regulated by platelets and by several proteinase inhibitors including, in order of decreasing importance, C1-inhibitor, α2antiplasmin, α1antitrypsin and antithrombin. Heparin has relatively little effect on the rate of inhibition of FXIa by antithrombin. The only known natural substrate for activated FXI (FXIa) is factor IX (Christmas factor) and the only cofactor required for this reaction is ionized calcium1-3.
References and Reviews
- Wuillemin WA, Minnema M, Meijers JCM, Roem D, Erenberg AJM, Nuijens JH, ten Cate H, Hack EC; Inactivation of Factor XIa in Human Plasma Assessed by Measuring Factor XIa-Protease Inhibitor Complexes: Major Role for C1-Inhibitor. Blood 85:1517, 1995.
- 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.
- Baglia FA, Seaman FS, Walsh, PN; The Apple 1 and 4 domains of Factor XI Act to Synergistically Promote the Surface-Mediated Activation of Factor XI by Factor XIIa. Blood 85:2078, 1995.