Influence of streptokinase on the interaction of ?-2-antiplasmin with different sites of plasmin molecule
Interaction of streptokinase and ?-2-antiplasmin with plasmin and plasminogen fragments was compared. Binding sites on the enzyme become half-saturated, streptokinase and ?-2-antiplasmin concentration being 8.5 and 30 nM, respectively. 6-Aminohexanoic acid in concentration of 20 mM reduces the adsorption of streptokinase and and ?-2-antiplasmin by 20 and 60%, respectively. From all the investigated fragments, streptokinase shows the greatest affinity for mini-plasminogen and ?-2-antiplasmin for kringles 1-3. Both proteins in the presence of 20 mM 6-aminohexanoic acid do not bind with kringle domains. Arginine dose 0.1 M does not influence streptokinase adsorption on mini-plasminogen and decreases the value of ?-2-antiplasmin binding with mini-plasminogen by 50%. The data obtained indicate that plasminogen molecule has the sites of the highest affinity for streptokinase on the serine-proteinase domain, however for ?-2-antiplasmin it is in the kringles 1-3.
Streptokinase with equimolar quantity in respect of ?-2-antiplasmin inhibits the adsorption of ?-2-antiplasmin on the plasmin by 70% and in the presence of 6-aminohexanoic acid it is inhibited completely. Addition of streptokinase also increases the influence of increasing concentration of the acid.
Inhibiting influence of streptokinase decreases, and that of 6-aminohexanoic acid increases, when plasmin is modified with diisopropylfluorophosphate in its active centre. At the same time maximum inhibition of streptokinase adsorption on the plasmin at different concentrations of ?-2-antiplasmin and 6-aminohexanoic acid accounts for only 20%.
We suppose that in the process of complex formation streptokinase competes with ?-2-antiplasmin for the binding sites on the catalytic domain of the plasmin.
Partial or complete blocking of the plasmin active centre contact zone by streptokinase effectively protects it from inhibition by ?-2-antiplasmin.
Published at the site: 2004-04-04
The original article in Russian is available for download in PDF format.