Boc-VPR-AMC, a specific, highly fluorogenic substrate for thrombin and the thrombin-staphylocoagulase complex. The thrombin assay has been used for the indirect determination of coagulation factor III. Trypsin, tryptase from rat mast cells, and two trypsin-like enzymes from sperm of the ascidian Halocynthia roretzi, acrosin and spermosin, also hydrolyze this substrate. Furthermore, Boc-VPR-AMC is cleaved by the Kex2 endoprotease (kexin, previously known as proteinase yscF), a membrane-bound, calcium-dependent serine protease from yeast α-cells. Kinetic data for Thrombin: kcat = 105, Km = 21 uM.