Domain formation in sphingomyelin/cholesterol mixed membranes studied by spin-label electron spin resonance spectroscopy
| Autor: | Derek Marsh, A. Alonso, M. I. Collado, F.M. Goñi |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Nitroxide mediated radical polymerization
Spectrometry Mass Electrospray Ionization Bilayer Lipid Bilayers Analytical chemistry Temperature Biochemistry Phase Transition law.invention Sphingomyelins Cyclic N-Oxides chemistry.chemical_compound Cholesterol chemistry law Phosphatidylcholine Phase (matter) Phosphatidylcholines lipids (amino acids peptides and proteins) Spin Labels Sphingomyelin Spectroscopy Spin label Electron paramagnetic resonance Gels |
| Zdroj: | Biochemistry. 44(12) |
| ISSN: | 0006-2960 |
| Popis: | Interactions of palmitoylsphingomyelin with cholesterol in multilamellar vesicles have been studied over a wide range of compositions and temperatures in excess water by using electron spin resonance (ESR) spectroscopy. Spin labels bearing the nitroxide free radical group on the 5 or 14 C-atom in either the sn-2 stearoyl chain of phosphatidylcholine (predominantly 1-palmitoyl) or the N-stearoyl chain of sphingomyelin were used to determine the mobility and ordering of the lipids in the different phases. Two-component ESR spectra of the 14-position spin labels demonstrate the coexistence first of gel (L(beta)) and liquid-ordered (L(o)) phases and then of liquid-ordered and liquid-disordered (L(alpha)) phases, with progressively increasing temperature. These phase coexistences are detected over a limited range of cholesterol contents. ESR spectra of the 5-position spin labels register an abrupt increase in ordering at the L(alpha)-L(o) transition and a biphasic response at the L(beta)-L(o) transition. Differences in outer splitting between the C14-labeled sphingomyelin and phosphatidylcholine probes are attributed to partial interdigitation of the sphingomyelin N-acyl chains across the bilayer plane in the L(o) state. In the region where the two fluid phases, L(alpha) and L(o), coexist, the rate at which lipids exchange between phases (< |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|