Description

Fibrinogen Polyclonal Antibody – Affinity Purified

Affinity’s Fibrinogen Polyclonal Antibody – Affinity Purified is the highest level of our Fibrinogen antibody family.  During the Antigen Affinity Purification process the IgG has had any non-specific immunoglobulin fraction eliminated which enriches the specificity of the remaining immunoglobulin towards the target antigen.  The result is a very high-purity product with a substantially higher titre than whole or purified IgG.  Our Fibrinogen Polyclonal Antibody – Affinity Purified is provided in a solution of HEPES buffered saline containing 50% glycerol (v/v) and is intended for applications such as immunoblotting, immunostaining of cells and several types of immunoassays where the higher signal-to-noise ratio achieved with this enriched product is required.

Product Code: SAFG-AP

Retail Product Size:0.5mg vial

Host Animal: Sheep Anti-Human Fibrinogen Polyclonal Antibody – Affinity Purified

Species Cross Reactivity: View Chart

Product Datasheet: Fibrinogen Polyclonal Antibody, affinity purified anti-human Sheep IgG

Description of Fibrinogen (Fg)

Human fibrinogen is a 340 kDa plasma protein produced in the liver.  Plasma concentrations are typically 1.7 – 3.5 g/L (5-10 μM).  The intact fibrinogen molecule consists of two identical subunits, each consisting of three non-identical polypeptide chains denoted as Aα, Bβ and γ.  The letters A and B in the Aα and Bβ chains designate, respectively, fibrinopeptide A (FpA, residues 1-16), and fibrinopeptide B (FpB, residues 1-14), which are cleaved by thrombin upon conversion of fibrinogen to fibrin.  The fibrin monomers polymerize in a half-overlap fashion to form insoluble fibrin fibrils. The polymerised fibrin is subsequently stabilized by activated Factor XIII that forms amide linkages between γ chains and, to a lesser extent, α chains of the fibrin molecules.

Proteolysis of fibrinogen by plasmin initially liberates C-terminal residues from the Aα chain to produce fragment X (intact D-E-D, which is still clottable).  Fragment X is further degraded to non-clottable fragments Y (D-E) and D.  Fragment Y can be digested into its constituent D and E fragments.  Proteolysis of crosslinked fibrin by plasmin results in fragment DD (D-Dimer consisting of the D domains of 2 fibrin molecules crosslinked via the γ chains), fragment E (central E domain) as well as DDE in which fragment E is non-covalently associated with DD.  The molecular weights of the cleavage fragments produced from human crosslinked fibrin are: 184 kDa for fragment DD, 92 kDa for D, 50 kDa for E, 1.54 kDa for FpA and 1.57 kDa for FpB.

Most of the fibrinogen in the circulation consists of 2 copies of each chain (Aα₂, Bβ₂, γ_A2), but in normal plasma approximately 10% of the fibrinogen molecules contain one γ_A chain and one variant γ chain (termed γ′), in which the c-terminal AGDV residues are replaced with the amino acid sequence VRPEHPAETEYDSLYPEDDL.  This variant fibrinogen is commonly referred to as fibrinogen gamma prime (γ_A/γ′) but has also been called fibrinogen 2 or peak 2 fibrinogen because it elutes separately from fibrinogen 1 (γ_A2) by ion exchange chromatography.  Residues 414-427 of the γ′ chain of fibrin gamma prime (contain a high-affinity binding site for exosite II of thrombin, which allows the active site of bound thrombin to remain available to interact with substrates while demonstrating resistance to heparin mediated inhibition by antithrombin^1-4.

References and Reviews

1. Hantgan RR, Francis CW, Marder VJ; Fibrinogen Structure and Physiology; in Hemostasis and Thrombosis, 3^rd Edition, eds. RW Colman, J Hirsh, VJ Marder and EW Salzman, pp 277-300, J.B. Lippincott Co., Philadelphia PA, USA, 1994.
2. Binnie CG, Lord ST; The Fibrinogen Sequences that Interact with Thrombin;  Blood 81,  pp 3186-3192, 1993.
3. Pospisil CH, Stafford AR, Fredenburgh JC, Weitz JI; Evidence that both Exosites on Thrombin Participate in Its High Affinity Interaction with Fibrin; JBC 278, pp 21584-21591, 2003.
4. Medved L, Weisel JW; Recommendations for Nomenclature on Fibrinogen and Fibrin; JTH 7, pp 355-359, 2009.