Fibrinogen Matsumoto V: a variant with a alpha 19 Arg -> Gly (AGG -> GGG) - Comparison between fibrin polymerization stimulated by thrombin or reptilase and fibrin monomer polymerization

Fibrinogen 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 A alpha 19 was replaced by GGG, resulting in the substitution of Arg-->Gly. Residue Aa19 has been shown to be one of the most important amino acids in the so-called 'A' site or a-chain knob. The thrombin-catalyz ed release of fibrinopeptide A from M-V fibrinogen was only slightly delaye d yet release of fibrinopeptide B was significantly delayed. Both thrombin- catalyzed fibrin polymerization and fibrin monomer polymerization were mark edly impaired compared to normal fibrinogen. In addition, reptilase-catalyz ed fibrin polymerization of M-V was much more impaired than thrombin-cataly zed fibrin polymerization. These results indicate 'B' and/or 'b' site of M- V fibrinogen play a more important role in thrombin-catalyzed fibrin polyme rization than that of normal control fibrinogen.