It has been known for many years [Mosseson MW & Finlayson]S.] Lab Clin Med 62:663, 1963] that human fibrinogen can be sufractionated chromatographically into two peaks called Peak ‘1’ and Peak ‘2’ Fibrinogen respectively. These fibrinogens differ from one another with respect to their gamma chain composition. Peak ‘1’ fibrinogen accounts for 85% of the total plasma fibrinogen and has two gamma-A chains, whereas Peak ‘2’ fibrinogen accounts for the remaining 15% and contains one gamma-A chain and one gamma chain per molecule. Peak ‘1’ fibrinogen contains mostly intact A-alpha subunit chains, is free of plasminogen, factor XIII, fibronectin, and other non-fibrinogen protein contaminants. Peak 1′ fibrinogen molecules each contain two copies of the platelet-binding gamma-A chain C-terminal sequence and are ideal substrates for factor XIII assay. Peak ‘2’ fibrinogen contains measurable amounts of factor XIII activity because the factor XIII B subunits bind to gamma chains and bring catalytic A subunits along with them. Thus Peak ‘2’ fibrinogen serves as a ‘carrier’ for factor XIII in blood. The gamma chain lacks the platelet recognition sequence but, like all gamma chains, become crosslinked to dimers by factor XIIIa.

Molecular Weights = 342,000 daltonsExtinction Coefficients (1%) = 15.1Clottability = > 95%

Peak 2 Fib Sample Certificate of Analysis