REGULATION WITH ?-2-ANTIPLASMIN OF Glu-PLASMINOGEN ACTIVATION BY TISSUE ACTIVATOR ON FIBRIN
Pallаdin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
Interaction of tissue plasminogen activator with ?-2-antiplasmin and its influence on tissue activator binding to fibrin was studied. ?-2-Antiplasmin decreases the binding of tissue activator to fibrin by 20%. The inhibitor formed a complex with tissue plasminogen activator (Kd 78.2 nM) and had no effect on amidolytic activity of the activator. The tissue activator binding to ?-2-antiplasmin decreases by 20–35% in the presence of 6-aminohexanoic acid. It indicates that not only kringle 2 of the tissue activator molecule takes part in complex formation with ?-2-antiplasmin, but also other activator domains. Two models were proposed to explain the ?-2-antiplasmin effect on the Glu-plasminogen activation by tissue activator on fibrin. In the first place, the inhibitor binds to fibrin in the site where the activator complex is localized. It can create steric hindrances for the proenzyme interaction with its activator on fibrin. In the second place, ?-2-antiplasmin in a complex with tissue plasminogen activator can bring to a change in the activator conformation and a decrease of its functional activity.
Key words: ?-2-antiplasmin, fibrin, tissue activator, inhibition of activation.
Published at the site: 2006-09-21
The original article in Ukrainian is available for download in PDF format.
© The Ukrainian Biochemical Journal