Modulation of staphylokinase-dependent plasminogen activation by mono- and divalent ions

Abstract

The effect of several ions (Cl -, Na + , K + , Ca 2+ ) on the rate of plasminogen (Pg) activation by recombinant staphylokinase (rSTA) is reported. Both monovalent and divalent ions affect the rate at which Pg is activated by rSTA, in a concentration-dependent manner (range 0-100 mM). In almost all cases, a decrease of the initial velocity of activation was observed. Cl -showed the most striking inhibitory effect at low concentrations (64% at 10 mM). However, in the presence of a fibrin surface, this inhibition was attenuated to 38%. Surprisingly, 10 mM Ca 2+ enhanced the Pg activation rate 21% when a polymerized fibrin matrix was present. These data support the idea that ions can modulate the rate of Pg activation through a mechanism that may be associated with changes in the molecular conformation of the zymogen. This effect is strongly dependent on the presence of a fibrin clot.

Cloning, high-level expression, purification and characterization of a staphylokinase variant, SakC, from Staphylococcus aureus QT08 in Escherichia coli BL21

“…In contrast, Ca 2+ and Mg 2+ showed an opposite effect on the rSak activity in this study and the native Sak activity studied by Vesterberg and Vesterberg (1972). The same results is also found in the report that Cl -, Na + , K + and Ca 2+ affected the rate at which plasminogen was activated by rSak (Yarzábal et al, 1999).…”