The liquid-ordered phase in sphingomyelincholesterol membranes as detected by the discrimination by oxygen transport (DOT) method

Wiśniewska, Anna; Subczynski, Witold K.

doi:10.2478/s11658-008-0012-y

Cited by 21 publications

(22 citation statements)

References 57 publications

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“…For example, phase boundaries for Chol/DMPC (dimyristoylphosphatidylcholine) membranes drawn based on measurements with stearic acid (Kusumi et al 1986) and phospholipid spin labels (Sankaram and Thompson 1991) overlap with phase boundaries obtained with other methods (Almeida et al 1992). Similarly, phase boundaries obtained with stearic acid spin labels (Wisniewska and Subczynski 2008) overlap appropriate boundaries in the phase diagram for Chol/palmitoylsphingomyelin (PSM), as presented by Almeida et al (de Almeida et al 2003). Both phospholipid- and cholesterol-analogue spin labels are distributed between the l o and l d phases coexisting in Chol/ESM membranes (see Fig.…”

Section: Introductionmentioning

confidence: 76%

“…We have developed electron paramagnetic resonance (EPR) spin-labeling methods that provide a unique opportunity to determine the lateral organization of lipid-bilayer membranes through the discrimination of coexisting membrane phases and/or domains (Ashikawa et al 1994; Kawasaki et al 2001; Raguz et al 2011; Raguz et al 2008; Raguz et al 2009; Subczynski et al 2007b; Wisniewska and Subczynski 2008). In some cases, these methods also allow us to characterize coexisting membrane phases and/or domains by profiles of alkyl-chain order, fluidity, hydrophobicity, and oxygen diffusion-concentration product in situ , without the need for physical separation (see Refs.…”

Section: Introductionmentioning

confidence: 99%

“…In model membranes made from a binary mixture of phospholipids and cholesterol, l o , l d , and solid-ordered phases were distinguished and characterized in different regions of a phase diagram when they formed a single phase or when two phases coexisted (Mainali et al 2011c; Subczynski et al 2007b; Wisniewska and Subczynski 2008). In membranes made from a ternary raft-forming mixture, the raft domain was also distinguished from bulk lipids using the DOT method (Wisniewska and Subczynski 2006a, b).…”

Section: Introductionmentioning

confidence: 99%

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Phases and domains in sphingomyelin–cholesterol membranes: structure and properties using EPR spin-labeling methods

2011

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EPR spin-labeling methods were used to investigate the order and fluidity of alkyl chains, the hydrophobicity of the membrane interior, and the order and motion of cholesterol molecules in coexisting phases and domains, or in a single phase of fluid-phase cholesterol/egg-sphingomyelin (Chol/ESM) membranes with a Chol/ESM mixing ratio from 0 to 3. A complete set of profiles for these properties was obtained for the liquid-disordered (ld) phase without cholesterol, for the liquid-ordered (lo) phase for the entire region of cholesterol solubility in this phase (from ~33 to 66 mol%), and for the lo-phase domain that coexists with the cholesterol bilayer domain (CBD). Alkyl chains in the lo phase are more ordered than in the ld pure ESM membrane. However, fluidity in the membrane center is greater. Also, the profile of hydrophobicity changed from a bell to a rectangular shape. These differences are enhanced when the cholesterol content in the lo phase is increased from 33 to 66 mol%, with clear brake-points between the C9 and C10 positions (approximately where the steroid-ring structure of cholesterol reaches into the membrane). The organization and motion of cholesterol molecules in the CBD are similar as in the lo-phase domain that coexists with the CBD.

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Section: Introductionmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Phases and domains in sphingomyelin–cholesterol membranes: structure and properties using EPR spin-labeling methods

2011

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“…This contrasts our conclusion that states that membrane properties, including barrier properties, are independent of phospholipid composition until the membrane is saturated with cholesterol. However, when the cholesterol concentration is low (~30 mol%), these membranes (especially those composed of saturated sphingomyelin) can be very rigid (Borchman et al, 1996; Kusumi et al, 1986; Wisniewska & Subczynski, 2008). …”

Section: Permeability Barriers and Hydrophobic Channels In Membranes mentioning

confidence: 99%

Functions of Cholesterol and the Cholesterol Bilayer Domain Specific to the Fiber-Cell Plasma Membrane of the Eye Lens

et al. 2011

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The most unique feature of the eye lens fiber-cell plasma membrane is its extremely high cholesterol content. Cholesterol saturates the bulk phospholipid bilayer and induces formation of immiscible cholesterol bilayer domains (CBDs) within the membrane. Our results (based on EPR spin-labeling experiments with lens-lipid membranes), along with a literature search, have allowed us to identify the significant functions of cholesterol specific to the fiber-cell plasma membrane, which are manifest through cholesterol-membrane interactions. The crucial role is played by the CBD. The presence of the CBD ensures that the surrounding phospholipid bilayer is saturated with cholesterol. The saturating cholesterol content in fiber-cell membranes keeps the bulk physical properties of lens-lipid membranes consistent and independent of changes in phospholipid composition. Thus, the CBD helps to maintain lens-membrane homeostasis when the membrane phospholipid composition changes significantly. The CBD raises the barrier for oxygen transport across the fiber-cell membrane, which should help to maintain a low oxygen concentration in the lens interior. It is hypothesized that the appearance of the CBD in the fiber-cell membrane is controlled by the phospholipid composition of the membrane. Saturation with cholesterol smoothes the phospholipid-bilayer surface, which should decrease light scattering and help to maintain lens transparency. Other functions of cholesterol include formation of hydrophobic and rigidity barriers across the bulk phospholipid-cholesterol domain and formation of hydrophobic channels in the central region of the membrane for transport of small, nonpolar molecules parallel to the membrane surface. In this review, we will provide data supporting these hypotheses.

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“…The properties of the liquid-ordered phase in DMPC/CHOL and sphingomyelin/ CHOL membranes have been characterized by this technique. 32,70 Also, the effect of carotenoids on membrane domain structure has been investigated in DMPC and DPPC membranes, and compared with the effect of CHOL. 71 In gel-phase membranes, two coexisting phases were discriminated in the presence of carotenoids, namely, the liquid-ordered-like and solid-ordered-like phases.…”

Section: Preparation Of Liposomesmentioning

confidence: 99%

Biomembrane models

Wiśniewska-Becker

Gruszecki

2013

Drug-Biomembrane Interaction Studies

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The liquid-ordered phase in sphingomyelincholesterol membranes as detected by the discrimination by oxygen transport (DOT) method

Cited by 21 publications

References 57 publications

Phases and domains in sphingomyelin–cholesterol membranes: structure and properties using EPR spin-labeling methods

Phases and domains in sphingomyelin–cholesterol membranes: structure and properties using EPR spin-labeling methods

Functions of Cholesterol and the Cholesterol Bilayer Domain Specific to the Fiber-Cell Plasma Membrane of the Eye Lens

Biomembrane models

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