Fibrinogen has a double function of yielding monomers that polymerize into fibrin and acting as a cofactor in platelet aggregation. Fibrinopeptide B is cleaved off the beta chain of fibrinogen by thrombin during fibrinogen conversion to fibrin.Human: pGlu-Gly-Val-Asn-Asp-Asn-Glu-Glu-Gly-Phe-Phe-Ser-Ala-Arg-OH or pEGVNDNEEGFFSAR-OH