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In vitro complex formation between cholesterol and alpha 1-proteinase inhibitor
1Department of Medicine, Malmö General Hospital, University of Lund, Sweden.
FEBS Letters
|February 1, 1993
Summary
Cholesterol interacts with alpha 1-proteinase inhibitor (alpha 1-PI) in vitro, reducing its activity and altering its properties. This suggests a noncovalent complex forms between cholesterol and alpha 1-PI.
Area of Science:
- Biochemistry
- Molecular Biology
- Proteomics
Background:
- Alpha 1-proteinase inhibitor (alpha 1-PI) is a crucial serine protease inhibitor.
- Cholesterol's role in protein interactions is not fully understood.
Purpose of the Study:
- To investigate the in vitro interaction between human alpha 1-proteinase inhibitor (alpha 1-PI) and cholesterol.
- To characterize the effects of cholesterol on alpha 1-PI's functional and physical properties.
Main Methods:
- Electrophoretic methods
- Gel chromatographic methods (gel filtration, SDS-PAGE)
- Assays for antiproteinase activity (antitryptic, antielastase)
- Immunoreactivity assays
Main Results:
- Cholesterol addition (1-20 mol/mol) retarded alpha 1-PI electrophoretic mobility.
- Antiproteinase activity was diminished; antielastase activity reduced by 50% at a 2:1 cholesterol/alpha 1-PI ratio.
- Gel filtration showed a shift in alpha 1-PI peak from 52 kDa to 67 kDa, indicating complex formation, while SDS-PAGE showed no size difference.
Conclusions:
- Cholesterol forms noncovalent complexes with alpha 1-proteinase inhibitor in vitro.
- Cholesterol binding impairs alpha 1-PI's antiproteinase function, particularly its antielastase activity.