Investigation of thrombin activity with PAR 1-based fluorogenic peptides.

Thrombin, a highly specific protease of blood coagulation, has two exosites that modulate its specificity. We designed two sets of synthetic substrate FRET peptides with 25- or 11- amino acids (aa) each, based on the PAR 1 sequence, to characterize the effect of exosite 1 engagement on substrate catalysis and preference. The 25-aa set encompassed a sequence binding to exosite 1, and structural modeling showed that binding to thrombin did not differ significantly from that of PAR 1 peptide.