Related Experiment Videos
Activation of human and bovine plasminogens by the microplasmin and streptokinase complex
1Department of Biochemistry, College of Medicine, National Cheng-Kung University, Tainan, Taiwan, R. O. C.
Abstract:
Human microplasmin is a catalytically active fragment of human plasmin. It consists of a 31-residue C-terminal peptide derived from the A chain bound through two disulfide bonds to the intact B chain of plasmin. It has similar amidolytic and proteolytic activities as the native human Lys-plasmin on a molar basis. Human microplasmin can form a complex with streptokinase, in a one to one stoichiometry, like the native human Lys-plasmin. The stoichiometric human microplasmin and streptokinase complex is an efficient activator of bovine plasminogen which can not be activated by streptokinase alone. The formation of human microplasmin.streptokinase complex was also directly demonstrated by a gel filtration column chromatography. Moreover, bovine plasminogen can not be activated by a mixture of bovine or porcine microplasmin and streptokinase. The equimolar complex of human microplasmin.streptokinase, human Lys-plasmin.streptokinase, or streptokinase alone has the same activator activity toward human Lys-plasminogen. The human microplasmin.streptokinase complex, however, has a significantly higher activator activity than human Lys-plasmin.streptokinase complex or streptokinase alone toward human Glu-plasminogen. The direct interaction between streptokinase and light chain domain of human plasmin is demonstrated in the complex formation. The difference in the activator activities of plasmins from various animal sources in complex with streptokinase therefore might be due to the difference in the compositions of light chains of plasmins.
Insights
Human microplasmin forms a potent complex with streptokinase, efficiently activating bovine plasminogen. This complex exhibits superior activator activity towards human Glu-plasminogen compared to other plasminogen activator complexes.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Human microplasmin is a catalytically active fragment of human plasmin.
- It shares amidolytic and proteolytic activities with native human Lys-plasmin.
- Microplasmin can form a 1:1 stoichiometric complex with streptokinase.
Purpose of the Study:
- To investigate the activation of bovine plasminogen by human microplasmin-streptokinase complex.
- To compare the activator activity of human microplasmin-streptokinase complex with other plasminogen activator complexes.
- To elucidate the role of light chain composition in plasmin-streptokinase interactions.
Main Methods:
- Formation and characterization of human microplasmin-streptokinase complex.
- Gel filtration column chromatography to demonstrate complex formation.
- Assays to measure amidolytic, proteolytic, and plasminogen activator activities.
Main Results:
- The human microplasmin-streptokinase complex efficiently activates bovine plasminogen, which streptokinase alone cannot activate.
- This complex shows significantly higher activator activity towards human Glu-plasminogen compared to human Lys-plasmin-streptokinase complex or streptokinase alone.
- Bovine and porcine microplasmin-streptokinase mixtures do not activate bovine plasminogen.
- Direct interaction between streptokinase and the light chain of human plasmin was demonstrated.
Conclusions:
- Human microplasmin-streptokinase complex is a highly efficient activator of bovine plasminogen.
- The enhanced activator activity of the human microplasmin-streptokinase complex towards human Glu-plasminogen suggests specific interactions.
- Differences in light chain composition of plasmin from various animal sources likely account for variations in streptokinase complex activity.