Different inhibition of one and two chain tissue plasminogen activator by a placental inhibitor studied with two tripeptide-p-nitroanilide substrates.
The interaction of tissue plasminogen activator derived from a melanoma cell line with a specific plasminogen activator inhibitor from placental tissue, which inhibits urokinase and tissue plasminogen activator but not plasmin, was studied. Tissue plasminogen activator exists in two forms, a one chain and a two chain molecule. It was found that the two enzyme species each form 1:1 complexes with the inhibitor and that the two chain enzyme binds the inhibitor very strongly, Ki = 3 X 10(-10) mol/l, whereas the one chain enzyme forms a much weaker complex, Ki is approximately 10(-7) to 10(-8) mol/l. Substrate hydrolysis is much more efficiently catalysed by the two chain plasminogen activator than by the one chain activator.
Astedt
B
B
Bladh
B
B
Christensen
U
U
Lecander
I
I
D000813:Anilides / Q000494:pharmacology*; D005260:Female; D005341:Fibrinolysin / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D008968:Molecular Conformation; D010920:Placenta / Q000201:enzymology*; D010960:Plasminogen Activators / Q000378:metabolism*; D011247:Pregnancy; D014568:Urokinase-Type Plasminogen Activator / Q000037:antagonists & inhibitors
D000813:Anilides; D010960:Plasminogen Activators; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator