Andrés YarzábalRamón SerranoJosep Puig Montada2026-03-222026-03-22199910.1590/s0100-879x1999000100005https://doi.org/10.1590/s0100-879x1999000100005https://andeanlibrary.org/handle/123456789/50707Citaciones: 5The effect of several ions (Cl-, Na+, K+, Ca2+) 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 Ca2+ 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.enStaphylokinaseDivalentFibrinZymogenChemistryBiophysicsIonRecombinant DNABiochemistryarticle