| Autor: |
John S. Allhusen, John C. Conboy, Dylan R. Kimball |
| Rok vydání: |
2016 |
| Předmět: |
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| Zdroj: |
Biophysical Journal. 110(3) |
| ISSN: |
0006-3495 |
| DOI: |
10.1016/j.bpj.2015.11.150 |
| Popis: |
Cholesterol is an integral component in eukaryotic cell membranes having an influential role in the phase behavior, lateral diffusion, and elasticity of lipid bilayers. One area which has not been widely explored is the role of cholesterol on the process of lipid flip-flop (or translocation). We have previously shown that cholesterol increases the rate of 1,2-diastearoyl-sn-glycero-3-phosphocholine (DSPC) flip-flop by decreasing the activation energy, enthalpy and entropy. Two important aspects of cholesterol are its amphiphilic nature and rigid ring structure. In this study, we have analyzed the impact of these characteristics on modulating DSPC flip-flop by studying two cholesterol analogues, 5α-cholestan-3β-ol (cholestanol) which lacks the double bond in ring B and 5-cholestene (cholestene) which lacks the hydroxyl group. The nonlinear optical technique of sum-frequency vibrational spectroscopy (SFVS) was used to measure the kinetics of DSPC lipid flip-flop when various concentrations of these sterols were present. The activation thermodynamics were retrieved from the kinetic data in order to interpret the thermodynamic role the hydroxyl group and double bond play in modulating DSPC flip-flop in membranes. The activation thermodynamics were found to be correlated with the elastic modulus of the membrane which was dependent upon the structure of the various analogues studied. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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