FLUOROMETRIC ASSAY FOR PLASMA PREKALLIKREIN USING PEPTIDYLMETHYL-COUMARINYL-AMIDE AS A SUBSTRATE

The content of prekallikrein in human plasma was determined by activation with acetone and kaolin, and subsequent measurement of the enzyme activity using carbobenzoxy-L-phenylalanyl-L-arginine 4-methylcoumarinyl-7-amide as substrate. The kallikrein generated was stable for 60 min after activation and at least 10% of the original concentration of both Hageman factor and high molecular weight kininogen are required to get complete activation of prekallikrein within this time period. When this method was compared to the radiochemical method employing 3H-TAME a similar sensitivity could be demonstrated. Plasmin and hog pancreatic kallikrein less readily hydrolyzed the amide substrate. © 1979.