Fibrinogen from human plasma: preparation by precipitation with heavy-metal coordination complex

Potassium tetrathiocyanato-(S)mercurate II [K(2)Hg(SCN)(4)] is used in a mild and rapid procedure for the isolation of human fibrinogen from fresh plasma. The final product, 94 to 99 percent of which is coagulable by thrombin, represents an average yield of 80 percent and is stable in solution. It is free of plasmin, streptokinase-activatable plasminogen, and coagulation factors II, V, VIII, X and XIII. Sedimentation analysis reveals a single peak with a sedimentation coefficient equal to 7.0S at infinite dilution. Immunodiffusion on cellulose acetate results in two precipitin lines with rabbit antiserum to whole human serum. The fibrinogen precipitates are unusual in that they are flocculent and readily redissolve.