Fibrinogen Matsumoto V: a Variant with Aα19 Arg → Gly (AGG → GGG)

Abstract

SummaryFibrinogen Matsumoto V (M-V) is a dysfibrinogen identified in a 52-year-old woman with systemic lupus erythematous. The triplet AGG encoding the amino acid residue Aα19 was replaced by GGG, resulting in the substitution of Arg→Gly. Residue Aα19 has been shown to be one of the most important amino acids in the so-called ‘A’ site or α-chain knob. The thrombin-catalyzed release of fibrinopeptide A from M-V fibrinogen was only slightly delayed yet release of fibrinopeptide B was significantly delayed. Both thrombin-catalyzed fibrin polymerization and fibrin monomer polymerization were markedly impaired compared to normal fibrinogen. In addition, reptilase-catalyzed fibrin polymerization of M-V was much more impaired than thrombin-catalyzed fibrin polymerization. These results indicate ‘B’ and/or ‘b’ site of M-V fibrinogen play a more important role in thrombin- catalyzed fibrin polymerization than that of normal control fibrinogen.