Fibrinogen is a large 340 kDa multimeric plasma glycoprotein involved in blood clotting. It is composed of two sets of three different polypeptide chains (, , and subunits) held together by 29 disulfide bonds.1 The six fibrinogen chains are assembled such that the amino terminal ends of all the subunits gather at the central core. Two globular domains are held together by three polypeptide chains that form a long coiled-coil structure.2 The and chains of fibrinogen contain sequences called the fibrinopeptide sequences, which prevent fibrinogen from spontaneously polymerizing.3 Conversion of fibrinogen into insoluble fibrin strands is catalyzed by the serine protEAse thrombin (Item No. 13188) during blood clot formation. Thrombin catalyses the rapid relEAse of fibrinopeptide A and then fibrinopeptide B after a lag phase. The fibrin monomers then spontaneously polymerize to form an insoluble gel. The polymerized fibrin is stabilized by noncovalent and electrostatic interactions promoted by factor XIIIa. Factor XIII, also known as fibrin stabilizing factor, is a transglutaminase that is activated by thrombin. The aggregated insoluble fibrin along with platelets are responsible for blocking damaged blood vessels during blood clotting.3Technical InformationSynonymsFBGFGPurityHomogeneous by SDS-PAGE. Clottable proteins: 95%SourceFibrinogen, purified from human plasma that has been shown by certified tests to be negative for HBsAg and for antibodies to HIV and HCV.MW chain isoform 1 (95 kDa), chain isoform 2 (69.8 kDa), chain (55.9 kDa) and isoform -B chain (51.5 kDa)FormulationA lyophilized powder. Lyophilized from 20 mM sodium citrate-HCl, pH 7.4.