Effect of low molecular weight dextran sulphate on plasmin activity measured with S-2251

The effect of low molecular weight dextran sulphate (DS) (molecular weight 3,900) on plasminogen activation by urokinase was investigated. When human plasma containing urokinase (100 IU/ml) was diluted with DS solution and acidified to pH 4, marked splitting activity of the substrate D-Val-Leu-Lys-pNA, which is a specific substrate for plasmin, appeared. Further, the precipitate obtained after centrifugation of diluted and acidified plasma exhibited remarkable substrate splitting activity. These results indicate that activation of plasminogen to plasmin by urokinase was enhanced by the low molecular weight dextran sulphate.