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Membrane-induced conformational change in human apolipoprotein H
1Department of Biological Sciences and Biotechnology, State Key Laboratory of Biomembrane, Tsinghua University, Beijing 100084, People's Republic of China.
The Biochemical Journal
|May 5, 2000
Summary
Apolipoprotein H (Apo H) undergoes significant structural changes when interacting with anionic phospholipid membranes. This conformational shift, involving alterations in alpha-helix and beta-sheet content, is crucial for Apo H
Area of Science:
- Biochemistry
- Biophysics
- Structural Biology
Background:
- Apolipoprotein H (Apo H) interaction with lipid membranes is key to its biological function.
- Previous studies indicate Apo H binds exclusively to membranes with anionic phospholipids.
Purpose of the Study:
- To investigate the membrane-induced conformational changes in Apo H.
- To correlate these structural alterations with Apo H's interaction with anionic lipid membranes.
Main Methods:
- Circular Dichroism (CD) spectroscopy was employed.
- Model systems included anionic-phospholipid-containing liposomes (DMPG, cardiolipin) and water/methanol mixtures mimicking membrane surface conditions.
Main Results:
- Apo H exhibited significant conformational changes upon binding to anionic liposomes.
- Interaction with DMPG liposomes increased alpha-helix content by 6.8%.
- Interaction with cardiolipin liposomes increased alpha-helix by 12.6% and decreased beta-sheet by 9%.
- Similar conformational changes were induced by water/methanol mixtures.
Conclusions:
- The association of Apo H with anionic lipid membranes is directly correlated with specific conformational changes in its secondary structure.
- These findings elucidate a fundamental aspect of Apo H's membrane interaction mechanism.