Qualitative changes in fibrinogen following exposure to agents used for preparation of fibrin monomers.

The solubility, clottability, thrombin clotting time and agarose gel chromatography pattern of human fibrinogen were studied after exposure to solvents commonly used to prepare fibrin monomers (0.0167 M acetic acid with 2.5 mM EDTA; 1 M NaBr, pH 5.2; 3.3 M urea, pH 7.4; 5 M urea, pH 7.4). When exposed to acetic acid at room temperature, fibrinogen precipitated almost immediately and quantitatively. Subsequent dialysis for 72 h against 0.3 M NaCl, pH 7.4, caused resolution of fibrinogen to a varying degree, the amount depending on the time of exposure. The redissolved fibrinogen showed reduced clottability, markedly shortened thrombin clotting time and a chromatographic profile that indicated large amounts of aggregates. Fibrinogen exposed to 1 M NaBr, pH 5.2, at room temperature for 1 h showed a slightly shortened thrombin clotting time and a broadened chromatographic profile. Exposure for 24 h to the same agent resulted in reduced solubility and clottability, a prolonged thrombin clotting time and progressive broadening of the chromatographic profile. Similar findings were obtained with fibrinogen exposed to 5 M urea, pH 7.4. Exposure to 3.3 M urea at pH 7.4 for 24 h, room temperature, led only to a moderate increase in solubility.