Related Experiment Videos
Opioid peptide interactions with lipid bilayer membranes
V Ramaswami1, R C Haaseth, T O Matsunaga
1C.S. Marvel Laboratories, Department of Chemistry, University of Arizona, Tucson 85721.
Biochimica Et Biophysica Acta
|August 24, 1992
Summary
The acyclic peptide DPDPE(SH)2 shows stronger interaction with phospholipid bilayers than the cyclic peptide DPDPE, indicated by higher permeability and altered membrane properties. This suggests flexibility enhances peptide-membrane interactions.
Area of Science:
- Biochemistry
- Biophysics
- Pharmacology
Background:
- Delta-opioid receptor selective peptides are crucial in pain management.
- Understanding peptide-membrane interactions is key to drug design.
- Phospholipid bilayers serve as models for biological membranes.
Purpose of the Study:
- To investigate the interaction of cyclic [D-Pen2, D-Pen5]-enkephalin (DPDPE) and its acyclic analog DPDPE(SH)2 with neutral phospholipid bilayers.
- To compare the membrane permeability and effects on bilayer phase transitions of DPDPE and DPDPE(SH)2.
Main Methods:
- Liposome-based peptide efflux assay to measure membrane permeability.
- Differential scanning calorimetry to assess the impact on lipid bilayer phase transition temperature (Tm) and cooperativity.
- Utilizing unilamellar liposomes composed of phosphatidylcholine, phosphatidylethanolamine, and cholesterol.
Main Results:
- Acyclic DPDPE(SH)2 exhibited significantly higher initial permeability (4.26 x 10^-12 cm s^-1) compared to cyclic DPDPE (0.91 x 10^-12 cm s^-1).
- DPDPE did not significantly alter the phase transition temperature (Tm) or enthalpy of DPPC bilayers.
- DPDPE(SH)2 caused a small but significant increase in DPPC Tm (0.2°C) and decreased cooperativity by 30%.
Conclusions:
- The increased flexibility of acyclic DPDPE(SH)2 leads to stronger interactions with phospholipid membranes compared to cyclic DPDPE.
- Peptide structure significantly influences membrane interaction dynamics and lipid packing.
- Findings provide insights into the structure-activity relationship of opioid peptides at the membrane interface.