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Modification of lipid phase behavior with membrane-bound cryoprotectants.
R P Goodrich1, T M Handel, J D Baldeschwieler
1Department of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena 91125.
Biochimica Et Biophysica Acta
|February 18, 1988
Summary
New cholesterol derivatives (triethoxycholesterol and triethoxycholesterol galactose) were synthesized to immobilize cryoprotectants on membrane surfaces. These compounds altered lipid membrane phase behavior, offering insights into cryoprotective strategies for synthetic and biological membranes.
Area of Science:
- Biochemistry
- Membrane Biophysics
- Materials Science
Background:
- Cholesterol is crucial for modulating cell membrane fluidity and phase behavior.
- Cryoprotectants stabilize biological and synthetic membranes during freezing.
- Immobilizing cryoprotectants at membrane surfaces could enhance their efficacy.
Purpose of the Study:
- To synthesize cholesterol derivatives with oxyethylene headgroups, some with terminal galactose.
- To investigate the effects of these derivatives on phosphatidylcholine and phosphatidylethanolamine membrane phase behavior.
- To understand how immobilized cryoprotectants influence membrane properties.
Main Methods:
- Synthesis of triethoxycholesterol (TEC) and triethoxycholesterol galactose (TEC-Gal) derivatives.
- Fluorescence polarization to assess membrane fluidity.
- 31P-NMR and freeze-fracture electron microscopy to analyze phase transitions.
Main Results:
- TEC and TEC-Gal derivatives modulated phosphatidylcholine phase behavior similarly to cholesterol.
- Unlike cholesterol, these derivatives reduced the Tm of dipalmitoylphosphatidylcholine (DPPC) concentration-dependently.
- A 20 mol% addition of derivatives increased the lamellar to hexagonal phase-transition temperature of DOPE dispersions by 10-20°C.
Conclusions:
- Cholesterol derivatives with immobilized oxyethylene headgroups can alter membrane phase behavior.
- These modifications suggest potential applications in cryoprotection for membranes.
- The study provides a foundation for designing novel cryoprotective agents based on cholesterol structures.