Bovine fibrinogen amino terminal labeled with fluorescein isothiocyanate (FITC). Prepared from fresh bovine plasma using several chromatographic steps. Plasminogen depleted by lysine affinity chromatography. Thaw in a 37°C water bath without agitation until completely liquid, then gently mix before use. Keep fibrinogen at 25-37°C, aliquot and flash freeze unused portion.