The biphasic nature and temperature dependence of the activation of human plasminogen by urokinase. A simple urokinase assay based on this phenomenon.
Activation of plasminogen is a biphasic process, the first phase is temperature independent, the second phase is not. The first phase of activation is completed immediately when urokinase (UK) is combined with plasminogen. At 4 degrees C the fibrinolytic activity generated in the first phase is directly proportional to the concentration of UK used for activation. This linear relationship permits the construction of a standard curve for the quantitative measurement of UK in samples with unknown concentrations of UK. The second, slower phase of activation follows the first only at higher temperatures (e.g. 28 degrees C), is limited by the plasminogen concentration, and is completed within 30 minutes of incubations. Activation of plasminogen by streptokinase under the same conditions follows a different pattern.
D001681:Biological Assay / Q000379:methods; D010450:Endopeptidases / Q000378:metabolism*; D005342:Fibrinolysis / Q000187:drug effects; D006801:Humans; D007668:Kidney / Q000201:enzymology; D010960:Plasminogen Activators; D013696:Temperature; D013997:Time Factors; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism* / Q000494:pharmacology
D010450:Endopeptidases; D010960:Plasminogen Activators; D014568:Urokinase-Type Plasminogen Activator