Structural Origins of Cholesterol Accelerated Lipid Flip-Flop Studied by Sum-Frequency Vibrational Spectroscopy
| Autor: | Dylan R. Kimball, John C. Conboy, John S. Allhusen |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Kinetics
Lipid Bilayers Infrared spectroscopy 02 engineering and technology 010402 general chemistry 01 natural sciences chemistry.chemical_compound Nuclear magnetic resonance Lipid translocation Materials Chemistry Physical and Theoretical Chemistry Lipid bilayer Molecular Structure Chemistry Cholesterol Cholestanol Spectrum Analysis technology industry and agriculture 021001 nanoscience & nanotechnology Sterol 0104 chemical sciences Surfaces Coatings and Films Crystallography Cholestene Phosphatidylcholines lipids (amino acids peptides and proteins) 0210 nano-technology |
| Zdroj: | The journal of physical chemistry. B. 120(12) |
| ISSN: | 1520-5207 |
| Popis: | The unique structure of cholesterol and its role in modulating lipid translocation (flip-flop) were examined using sum-frequency vibrational spectroscopy (SFVS). Two structural analogues of cholesterol--cholestanol and cholestene--were examined to explore the influence of ring rigidity and amphiphilicity on controlling distearoylphosphocholine (DSPC) flip-flop. Kinetic rates for DSPC flip-flop were determined as a function of sterol concentration and temperature. All three sterols increased the rate of DSPC flip-flop in a concentration-dependent manner following the order cholestenecholestanolcholesterol. Rates of DSPC flip-flop were used to calculate the thermodynamic activation free energy barrier (ΔG(‡)) in the presence of cholesterol, cholestanol, and cholestene. The acyl chain gauche content of DSPC, mean lipid area, and membrane compressibility were correlated to observed trends in ΔG(‡). ΔG(‡) for DSPC flip-flop showed a strong positive correlation with the molar compression modulus (K*) of the membrane, influenced by the type and concentration of the sterol added. Interestingly, cholesterol is distinctive in maintaining invariant membrane compressibility over the range of 2-10 mol %. The results in this study demonstrate that the compression modulus of a membrane plays a significant role in moderating ΔG(‡) and the kinetics of native, protein-free, lipid translocation in membranes. |
| Databáze: | OpenAIRE |
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