Rectangular solid domains in ceramide–cholesterol monolayers – 2D crystals

Ekelund, Katarina; Eriksson, L.; Sparr, Emma

doi:10.1016/s0005-2736(00)00157-7

Cited by 12 publications

(16 citation statements)

References 16 publications

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“…Because the height of cholesterol and palmitic acid molecules is relatively similar, it is not clear whether AFM would distinguish domains enriched in one of the two components. Another AFM study showed the formation of small rectangular domains in monolayers prepared from cholesterol and ceramides (Ekelund et al, 2000). These domains were interpreted as ceramides domains surrounded by a cholesterolrich phase.…”

Section: Resultsmentioning

confidence: 96%

“…This conclusion was inferred from the analysis of the methylene deformation and rocking bands, and it was also concluded from this approach that the domains would include at least 100 molecules and that their composition was at least 90% enriched in palmitic acid or ceramides. Finally, recent experiments in atomic force microscopy (AFM) on Langmuir-Blodgett monolayers formed with SC lipid model mixtures indicate phase separations leading to formation of domains that were proposed to be enriched in ceramides (ten Grotenhuis et al, 1996;Ekelund et al, 2000). Forslind (1994) proposed that the organization of SC lipids can be described by crystalline domains surrounded with disordered grain border regions, forming "the domain mosaic model of the skin barrier."…”

Section: Introductionmentioning

confidence: 99%

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Direct Observation of Domains in Model Stratum Corneum Lipid Mixtures by Raman Microspectroscopy

Percot

Lafleur

2001

Biophysical Journal

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Several studies on intact and model stratum corneum (SC), the top layer of the epidermis, have suggested the presence of crystalline domains. In the present work, we used micro-Raman mapping to detect lipid domains in model lipid mixtures formed by an equimolar mixture of ceramides, cholesterol, and palmitic acid, the three main lipid species of SC. We were able to determine the spatial distribution of the three compounds individually based on the systematic analysis of band areas. As a control, we studied freeze-dried lipid mixtures, and the Raman microspectroscopy reported faithfully the homogeneous distribution of the three compounds. Spectral mapping was then performed on hydrated equimolar mixtures carefully annealed. In this case, clear phase separations were observed. Domains enriched in cholesterol, ceramides, or palmitic acid with a size of a few tens of square microns were detected. These findings constitute the first direct evidence of the formation of heterogeneous domains in the SC lipid models in a bulk phase. Raman microspectroscopy is an innovative approach to characterize the conditions leading to the formation of domains and provides new insights into the understanding of the skin barrier.

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Section: Resultsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Direct Observation of Domains in Model Stratum Corneum Lipid Mixtures by Raman Microspectroscopy

Percot

Lafleur

2001

Biophysical Journal

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“…The phase behavior and monolayer properties of many sphingolipids have been investigated in detail before (4)(5)(6)(29)(30)(31). Ceramide forms solid monolayers that are characterized by an asymmetry in the hydrocarbon chains.…”

Section: Introductionmentioning

confidence: 99%

Structure of Ceramide-1-Phosphate at the Air-Water Solution Interface in the Absence and Presence of Ca2+

Kooijman

Vaknin

et al. 2009

Biophysical Journal

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Ceramide-1-phosphate, the phosphorylated form of ceramide, gained attention recently due to its diverse intracellular roles, in particular in inflammation mediated by cPLA(2)alpha. However, surprisingly little is known about the physical chemical properties of this lipid and its potential impact on physiological function. For example, the presence of Ca(2+) is indispensable for the interaction of Cer-1-P with the C2 domain of cPLA(2)alpha. We report on the structure and morphology of Cer-1-P in monomolecular layers at the air/water solution interface in the absence and presence of Ca(2+) using diverse biophysical techniques, including synchrotron x-ray reflectivity and grazing angle diffraction, to gain insight into the role and function of Cer-1-P in biomembranes. We show that relatively small changes in pH and the presence of monovalent cations dramatically affect the behavior of Cer-1-P. On pure water Cer-1-P forms a solid monolayer despite the negative charge of the phosphomonoester headgroup. In contrast, pH 7.2 buffer yields a considerably less solid-like monolayer, indicating that charge-charge repulsion becomes important at higher pH. Calcium was found to bind strongly to the headgroup of Cer-1-P even in the presence of a 100-fold larger Na(+) concentration. Analysis of the x-ray reflectivity data allowed us to estimate how much Ca(2+) is bound to the headgroup, approximately 0.5 Ca(2+) and approximately 1.0 Ca(2+) ions per Cer-1-P molecule for the water and buffer subphase respectively. These results can be qualitatively understood based on the molecular structure of Cer-1-P and the electrostatic/hydrogen-bond interactions of its phosphomonoester headgroup. Biological implications of our results are also discussed.

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“…Ten Grotenhuis et al, 1996;SchaVer et al, 1999;Ekelund et al, 2000;Sparr et al, 2001). AFM on deposited monolayer Wlms beneWts from high lateral and vertical resolution (a few Ångströms) and simplicity of sample preparation (no decoration or conducting coating is needed).…”

Section: Introductionmentioning

confidence: 99%

Human stratum corneum lipid organization as observed by atomic force microscopy on Langmuir–Blodgett films

Norlén

Gil

Simonsen

et al. 2007

Journal of Structural Biology

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Rectangular solid domains in ceramide–cholesterol monolayers – 2D crystals

Cited by 12 publications

References 16 publications

Direct Observation of Domains in Model Stratum Corneum Lipid Mixtures by Raman Microspectroscopy

Direct Observation of Domains in Model Stratum Corneum Lipid Mixtures by Raman Microspectroscopy

Structure of Ceramide-1-Phosphate at the Air-Water Solution Interface in the Absence and Presence of Ca2+

Human stratum corneum lipid organization as observed by atomic force microscopy on Langmuir–Blodgett films

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