N-ethoxycarbonyl-D-phenylalanyl-L-prolyl-alpha-azalysine p-nitrophenyl ester: A novel, high selective and optimal chromogenic active site titrant for human and bovine alpha-, beta- and gamma-thrombin

The serine proteinase catalyzed hydrolysis of N-ethoxycarbonyl-D-phenylalanyl-L-prolyl-alpha-p-nitrophenyl ester (Eoc-D-Phe-Pro-azaLys-ONp) was investigated at pH 6.2 and 21.0 degrees C. The results are consistent with the minimum three-step catalytic mechanism. The acylation step is rare limiting for human (Lys 77 species) and porcine plasmin, and for bovine beta-trypsin, the deacylation rate being limiting, on the other hand,for human and bovine alpha-, beta- and gamma-thrombin. Moreover, the M(r) 33,000 species of human urokinase and the neuraminidase-treated porcine pancreatic beta-kallikrein-B do not catalyze the hydrolysis of the tripeptide. According to the specificity properties of the serine proteinases considered, Eoc-D-Phe-Pro-azaLys-ONp shows the characteristics of a novel, high selective and optimal chromogenic active site titrant for human and bovine alpha-, beta- and gamma-thrombin. (C) 1996 Academic Press, Inc.