Cholesterol Monohydrate Nucleation in Ultrathin Films on Water

Rapaport, Hanna; Kuzmenko, Ivan; Lafont, Sylvaine; Kjær, Kristian; Howes, P.B.; Als‐Nielsen, J.; Lahav, Meir; Leiserowitz, Leslie

doi:10.1016/s0006-3495(01)75915-2

Cited by 87 publications

(148 citation statements)

References 23 publications

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“…The registration of the bilayers can be altered by a different pattern of water molecules between the layers. An illustrative analogy is the crystal structure of the cholesterol derivative stigmasterol, which has been reported recently (29). The overall packing of stigmasterol molecules is similar to that of cholesterol, but with less than one water molecule per sterol, thus forming a stigmasterol hemihydrate.…”

Section: Discussionmentioning

confidence: 91%

“…Recent studies of cholesterol crystal nucleation upon an air-water interface (29,30), as well as diffraction electron microscopy studies of cholesterol films in bile (24), cast additional light on the pathway by which helical ribbons may be formed. Both studies show that thin cholesterol crystals have rectangular unit cell, with a ϭ 10 and b ϭ 7.5 Å.…”

Section: Discussionmentioning

confidence: 99%

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Structure of cholesterol helical ribbons and self-assembling biological springs

Khaykovich

Hossain

McManus³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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We report the results of x-ray-scattering studies of individual helical ribbons formed in multicomponent solutions of cholesterol solubilized by various surfactants. The solutions were chemically defined lipid concentrate (CDLC) and model bile. In these and many analogous multicomponent surfactant-cholesterol solutions, helical ribbons of two well defined pitch angles, namely 11°and 54°, are formed. We have suggested previously that this remarkable stability results from an underlying crystalline structure of the sterol ribbon strips. Using a synchrotron x-ray source, we have indeed observed Bragg reflections from individual ribbons having 11°pitch angle. We have been able to deduce the parameters of the unit cell. The crystal structure of these ribbons is similar to that of cholesterol monohydrate, with the important difference that the length of the unit cell perpendicular to the cholesterol layers is tripled. We discuss possible origins for this triplication as well as the connection between the crystalline structure and the geometrical form of the helical ribbons.crystal structure ͉ x-ray diffraction ͉ crystallization ͉ surfactants S elf assembly of helical ribbons in complex fluids is an interesting phenomenon, which poses fundamental questions about the molecular structure, elastic properties, and kinetic evolution of these objects. In particular, quaternary solutions, which contain cholesterol, nonionic surfactants, and lipids, spontaneously form helical ribbons with characteristic pitch angles of 11°and 54°. These helical ribbons are long rectangular strips, which curl along a cylindrical surface. These objects were discovered in human gallbladder bile, where they form spontaneously upon the dilution of bile. This dilution produces a solution supersaturated with respect to cholesterol (1). Formation of similar helical ribbons has been later reported in Ͼ20 different solutions with various sterols analogous to cholesterol, surfactants, and phospholipids or fatty acids (2). These helical ribbons form in a variety of axial lengths, widths, and radii. Remarkably, however, almost all have pitch angles of either 11°o r 54°. Several theoretical models have been proposed to explain the formation and properties of helical ribbons, which sometimes form in complex fluids containing chiral amphiphilic molecules (3-10). These theories were designed to describe the helical ribbons in solutions containing a single species of phospholipids, which can form bilayers. Therefore, the ribbons were modeled theoretically as fluid bilayers, where hydrophobic carbon chains are sandwiched between hydrophilic head groups. Calculations of the properties of such membranes are usually based on the curvature elasticity model (11), which is founded on general physical arguments about the dependence of the fluid membrane elastic free energy on its curvature. Based on this model, subsequent theories attempted to explain the geometrical and elastic properties of the helical ribbons. For example, the formation of helices is attributed to b...

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Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Structure of cholesterol helical ribbons and self-assembling biological springs

Khaykovich

Hossain

McManus³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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“…It was recently shown that cholesterol enriched macrophage cells form cholesterol crystals near the cytoplasm membrane, 44 and it was suggested that these crystals nucleate at the lipid membrane. 20, 40, 45 We hereby demonstrate that the nucleation of cholesterol crystals can occur within DPPC:Chol:POPC bilayers and discuss the conditions for nucleation.…”

Section: Introductionmentioning

confidence: 80%

Crystalline Domain Structure and Cholesterol Crystal Nucleation in Single Hydrated DPPC:Cholesterol:POPC Bilayers

2010

Self Cite

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Grazing incidence X-ray diffraction measurements were performed on single hydrated bilayers and monolayers of DPPC:Cholesterol:POPC at varying concentrations. There are substantial differences in the phase and structure behavior of the crystalline domains formed within the bilayers relative to the corresponding monolayers, due to interactions between the opposing leaflets. Depending on the lipid composition, these interactions led to phase separation, changes in molecular tilt angle, or formation of cholesterol crystals. In monolayers, DPPC and cholesterol form a single crystalline phase at all compositions studied. In bilayers, a second crystalline phase appears when cholesterol levels are increased: domains of cholesterol and DPPC form monolayer thick crystals where each of the lipid leaflets diffracts independently, whereas excess cholesterol forms cholesterol bilayer thick crystals at a DPPC:Chol ratio < 46:54 ( 2 mol %. The nucleation of the cholesterol crystals occurs at concentrations relevant to the actual cell plasma membrane composition.

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“…Similarly, the abundant HHP product from CholSO 4 ozonolysis is attributed to a relatively low water density in the CholSO 4 interfacial layer. At the air-water interface, Chol assembles in ordered crystalline structures up to three molecular layers thick [34,35]. Analysis using X-ray diffraction indicates that the Chol crystalline phase on the liquid surface comprises Chol monohydrate crystallites [35].…”

Section: Air-liquid Interfacial Reaction Of Cholso 4 With Omentioning

confidence: 99%

“…At the air-water interface, Chol assembles in ordered crystalline structures up to three molecular layers thick [34,35]. Analysis using X-ray diffraction indicates that the Chol crystalline phase on the liquid surface comprises Chol monohydrate crystallites [35]. It is expected that CholSO 4 interacts with water molecules to a greater extent than Chol due to its anionic sulfate head group.…”

Section: Air-liquid Interfacial Reaction Of Cholso 4 With Omentioning

confidence: 99%

Studying Interfacial Reactions of Cholesterol Sulfate in an Unsaturated Phosphatidylglycerol Layer with Ozone Using Field Induced Droplet Ionization Mass Spectrometry

Choi

Rhee

et al. 2011

J. Am. Soc. Mass Spectrom.

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Field-induced droplet ionization (FIDI) is a recently developed ionization technique that can transferions from the surface of microliter droplets to the gas phase intact. The air-liquid interfacial reactions of cholesterol sulfate (CholSO 4 ) in a 1-palmitoyl-2-oleoyl-sn-phosphatidylglycerol (POPG) surfactant layer with ozone (O 3 ) are investigated using field-induced droplet ionization mass spectrometry (FIDI-MS). Time-resolved studies of interfacial ozonolysis of CholSO 4 reveal that water plays an important role in forming oxygenated products. An epoxide derivative is observed as a major product of CholSO 4 oxidation in the FIDI-MS spectrum after exposure of the droplet to O 3 for 5 s. The abundance of the epoxide product then decreases with continued O 3 exposure as the finite number of water molecules at the air-liquid interface becomes exhausted. Competitive oxidation of CholSO 4 and POPG is observed when they are present together in a lipid surfactant layer at the air-liquid interface. Competitive reactions of CholSO 4 and POPG with O 3 suggest that CholSO 4 is present with POPG as a well-mixed interfacial layer. Compared with CholSO 4 and POPG alone, the overall ozonolysis rates of both CholSO 4 and POPG are reduced in a mixed layer, suggesting the double bonds of both molecules are shielded by additional hydrocarbons from one another. Molecular dynamics simulations of a monolayer comprising POPG and CholSO 4 correlate well with experimental observations and provide a detailed picture of the interactions between CholSO 4 , lipids, and water molecules in the interfacial region.

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Cholesterol Monohydrate Nucleation in Ultrathin Films on Water

Cited by 87 publications

References 23 publications

Structure of cholesterol helical ribbons and self-assembling biological springs

Structure of cholesterol helical ribbons and self-assembling biological springs

Crystalline Domain Structure and Cholesterol Crystal Nucleation in Single Hydrated DPPC:Cholesterol:POPC Bilayers

Studying Interfacial Reactions of Cholesterol Sulfate in an Unsaturated Phosphatidylglycerol Layer with Ozone Using Field Induced Droplet Ionization Mass Spectrometry

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