Catalytic properties of bovine alpha-thrombin: a comparative steady-state and pre-steady-state study.

Values of steady-state and pre-steady-state parameters for the bovine alpha-thrombin-catalyzed hydrolysis of ZArgONp and ZLysONp have been determined between pH 2.5 and 8 (I = 0.1 M) at 21 +/- 0.5 degree C. Kinetic properties of bovine alpha-thrombin have been analyzed in parallel with those of porcine pancreatic beta-kallikrein-B and bovine beta-trypsin, all acting on cationic substrates. The different primary specificity and catalytic behaviour of these three serine proteinases reflect subtle structural differences at their S1 subsite, especially at residue positions 190, 221 and 226 as well as in the 217-219 segment.