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Human urinary prokallikrein: rapid purification and model activation by trypsin
Biochemistry International
|August 1, 1986
Summary
Human urinary prokallikrein was purified using a three-step method. Trypsin rapidly activated prokallikrein, suggesting propeptide release is key to initial kallikrein activity.
Area of Science:
- Biochemistry
- Enzymology
Background:
- Human urinary prokallikrein is a key enzyme in the kallikrein-kinin system.
- Understanding its activation mechanism is crucial for physiological and pathological studies.
Purpose of the Study:
- To develop a streamlined purification method for human urinary prokallikrein.
- To investigate the activation kinetics and mechanism of human urinary prokallikrein by trypsin.
Main Methods:
- A three-step chromatographic procedure was employed for complete purification.
- Activation kinetics were studied using trypsin digestion.
- Molecular weight, Km, and Vmax were determined.
Main Results:
- Complete purification of human urinary prokallikrein was achieved.
- Trypsin induced rapid activation of prokallikrein, followed by a slow increase in activity.
- The rapidly activated state exhibited similar kinetic parameters (Km, Vmax) and molecular weight to active kallikrein.
Conclusions:
- The initial rapid activation of human urinary prokallikrein by trypsin is attributed to propeptide release.
- The subsequent slow activity increase likely results from limited hydrolysis at sites unrelated to the active site.