= Fibrinopeptide
A <fibrinopeptide> is a short <peptide> released from <fibrinogen> during its proteolytic conversion toward <fibrin>. The principal forms are <Fibrinopeptide A> and <Fibrinopeptide B>, cleaved from the amino-terminal regions of the A-alpha and B-beta chains, respectively. Their removal exposes molecular sites that promote <fibrin> assembly.<Steady state kinetic parameters for the thrombin-catalyzed conversion of human fibrinogen to fibrin by D. L. Higgins and others>[1983, abstract: chain identity and thrombin-mediated peptide release]{ref}
Experiments measured the release of the two <fibrinopeptides> separately and related their kinetics to <fibrin> <polymerization>. Under the tested solution conditions, release of <Fibrinopeptide A> preceded the main release of <Fibrinopeptide B>, with assembly affecting the later step.<Steady state kinetic parameters for the thrombin-catalyzed conversion of human fibrinogen to fibrin by D. L. Higgins and others>[Abstract: predominant pathway and polymerization-dependent release]{ref}
The small released fragments and the remaining network-forming material have different roles. For a stipulated counting example, if each converted <fibrinogen> molecule releases two copies of one <fibrinopeptide>, converting 3 nmol generates 6 nmol of that fragment. The amount recovered can report the extent of cleavage; it does not by itself determine the final clot's stiffness or network geometry.
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