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Preferential binding of apolipoprotein E derived peptides with oxidized phospholipid
Abhay H Pande1, Rajan K Tripathy
1Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar (Mohali), Punjab 160062, India. apande@niper.ac.in
Biochemical and Biophysical Research Communications
|January 23, 2009
Summary
Apolipoprotein E (apoE) peptide fragments show increased affinity for oxidized phospholipid membranes. This preferential binding suggests a role for apoE in the anti-oxidative properties of cell membranes.
Area of Science:
- Biochemistry
- Molecular Biology
- Lipid Metabolism
Background:
- Apolipoprotein E (apoE) is crucial for lipid transport and metabolism.
- The C-terminal domain of apoE contains high-affinity lipid-binding sites.
- Interactions of apoE with non-oxidized membranes are known, but not with oxidized ones.
Purpose of the Study:
- To investigate the interaction of apoE C-terminal peptide sequences with oxidized phospholipid membranes.
- To compare binding affinity to membranes with and without oxidized phospholipids, specifically 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazePC).
Main Methods:
- Utilized amphipathic helical peptide sequences from apoE's C-terminal domain.
- Studied peptide interaction with membrane vesicles using fluorescence emission maxima, acrylamide quenching of tryptophan residues, and resonance energy transfer (RET) analysis for binding constants.
Main Results:
- ApoE peptide sequences (202-223, 245-266, 268-289) exhibited higher affinity for PazePC-containing membranes compared to control membranes.
- Binding affinity decreased in the presence of divalent cations (1mM) or NaCl (50mM), indicating potential electrostatic interactions.
- Peptides demonstrated preferential binding to oxidized phospholipid membranes.
Conclusions:
- ApoE C-terminal fragments preferentially bind to membranes containing oxidized phospholipids (PazePC).
- Electrostatic interactions may play a role in the binding mechanism.
- This preferential binding could contribute to the anti-oxidative functions of apolipoprotein E.
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