Prourokinase (Pro-UK) is the precursor of two chain
urokinase (UK), a serine protease that can activate
plasminogen to plasmin.
Pro-UK can be converted into UK via hydrolysis of the Lys-158-Ile-159 peptide
bond by certain proteases such as plasmin, kallikrein or cathepsin B.
Although Pro-UK is a zymogen and is inert in
plasma, it has a higher intrinsic activity than most other zymogen. In the presence of fibrin fragment E, plasminogen activation by the intrinsic activity of
Pro-UK is promoted 500-fold, giving it an activity comparable to UK. Pro-UK
is a fibrin specific thrombolytic agent consisting
of 411 amino acids with 12 disulfide bonds. Its molecular weight is 54,000.
Greater than 90% by SDS-PAGE.
After activation by plasmin, its specific activity
is greater than 100,000 IU/mg. Without activation it only has less than 1% of
After activation by plasmin, 1 nM
UK will cause a change in absorbance of 0.001 at 405 nm in 1 minute at room temperature
in 100 ul 0.05 M Tris-HCl,
0.1 M NaCl, pH 7.4, using S2444 (0.6 mM) as the substrate.
White lyophilized powder or solution.
The lyophilized powder is best stored desiccated below 0°C. After it is
reconstituted with sterile water or other buffered solutions (we recommend to
dissolve pro-UK with 5mM HAc-NaAc, pH 4.8), it
should be stored at -20°C.