Kinetic Differences of Plasmins from Eight Mammalian Species: N-Terminal Activations and Sequences

Abstract

The paper determines the kinetic parameters of plasmins from eight species of mammals and their N-terminals. They were purified by the same methods (affinity chromatography and ion exchange) and activated with urokinase, starting from a common concentration and its kinetics judged according to Lineweaver-Burk coordinates. For such purpose, MichaelisMenten enzyme kinetics, which is widely used in the study of enzymes, was implemented. When compared with the molecular weight standard used, all plasminogen showed a purity exceeding 95% and a 92 kDa band on electrophoresis. Equine and canine plasmins showed the same K_M due to the chromogenic substrate (0.438 mM), this being the one with the highest affinity in this study, and the human being the one with the lower affinity (5.3 mM). The catalytic constant and the conversion rate of the chromogenic substrate to product were also determined. The N-terminals of the plasminogens of the eight species were determined, and differences were found between humans and animals, as well as between some animals. Only pigs and sheep showed no differences in their N-terminal (DPPDDY). The unification of the method for purification of plasminogens for any species was demonstrated, as well as the kinetic differences of the eight plasmins studied and the similarities and differences in the sequence the N-terminals of the eight species.