Application of small-angle neutron diffraction to the localization of general anesthetics in model membranes

Hrubovčák, Pavol; Kondela, Tomáš; Ermakova, E. V.; Kučerka, Norbert

doi:10.1007/s00249-019-01370-7

Cited by 6 publications

(3 citation statements)

References 42 publications

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“…The total measurement time for one sample at a given contrast condition took about 2.5–3 h. The bilayer stability was confirmed by performing the scan at the first position of the detector repeatedly, while checking the reproducibility of the intensity and position of each reflection. The analysis of neutron diffraction data was performed by using the ILL’s LAMP software and our own computer code in the rocking curve representation because of its natural compatibility with the instrument setup. Figure presents an example of the rocking curves.…”

Section: Methodsmentioning

confidence: 99%

“…In addition, the high quality of the samples is demonstrated by the detection of 5 orders of reflection for DOPC samples and up to 7 orders for DPPC samples. The data obtained from fitting the rocking curves comprise the peak position ( q h ) and its amplitude ( I h ) necessary for the further analysis and bilayer structure reconstruction, in particular for the reconstruction of neutron scattering length density (NSLD) profiles (see the Supporting Information for more details) …”

Section: Methodsmentioning

confidence: 99%

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Cation–Zwitterionic Lipid Interactions Are Affected by the Lateral Area per Lipid

Kučerka

Ermakova²,

Dushanov

et al. 2020

Langmuir

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Interactions of the divalent cations Ca2+ and Mg2+ with the zwitterionic lipid bilayers prepared of a fully saturated dipalmitoylphosphatidylcholine (DPPC) or a di-monounsaturated dioleoylphosphatidylcholine (DOPC) were studied by using the neutron scattering methods and molecular dynamics simulations. The effect on the bilayer structural properties confirms the direct interactions in all cases studied. The changes are observed in the bilayer thickness and lateral area. The extent of these structural changes, moreover, suggests various mechanisms of the cation–lipid interactions. First, we have observed a small difference when studying DPPC bilayers in the gel and fluid phases, with somewhat larger effects in the former case. Second, the hydration proved to be a factor in the case of DOPC bilayers, with the larger effects in the case of less hydrated systems. Most importantly, however, there was a qualitative difference between the results of the fully hydrated DOPC bilayers and the others examined. These observations then prompt us to suggest an interaction model that is plausibly governed by the lateral area of lipid, though affected indirectly also by the hydration level. Namely, when the interlipid distance is small enough to allow for the multiple lipid–ion interactions, the lipid–ion–lipid bridges are formed. The bridges impose strong attractions that increase the order of lipid hydrocarbon chains, resulting in the bilayer thickening. In the other case, when the interlipid distance extends beyond a limiting length corresponding to the area per lipid of ∼65 Å2, Mg2+ and Ca2+ continue to interact with the lipid groups by forming the separate ion–lipid pairs. As the interactions proposed affect the lipid membrane structure in the lateral direction, they may prove to play their role in other mechanisms lying within the membrane multicomponent systems and regulating for example the lipid–peptide–ion interactions.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Cation–Zwitterionic Lipid Interactions Are Affected by the Lateral Area per Lipid

Kučerka

Ermakova²,

Dushanov

et al. 2020

Langmuir

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“…The form factor errors δ F h were derived from the uncertainties of experimental intensities expressed as the square root of the integrated intensity I h of each reflection and included in the calculations of the uncertainties of the reconstructed NSLD profiles. Note that the approach of NSLD error estimation is not unified in the literature. ,,,− The uncertainties of the relative NSLD profile (δρ ( z ) ) were calculated according to ref from the following equation δ ρ false( z false) = prefix± true[ prefix∑ h = 1 h max ( δ F h ) 2 ⁢ cos 2 true( 2 π h z d true) true] 1 / 2 …”

Section: Methodsmentioning

confidence: 99%

Polymorphism, Nanostructures, and Barrier Properties of Ceramide-Based Lipid Films

et al. 2022

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Ceramides belong to sphingolipids, an important group of cellular and extracellular lipids. Their physiological functions range from cell signaling to participation in the formation of barriers against water evaporation. In the skin, they are essential for the permeability barrier, together with free fatty acids and cholesterol. We examined the periodical structure and permeability of lipid films composed of ceramides (Cer; namely, N-lignoceroyl 6-hydroxysphingosine, CerNH24, and N-lignoceroyl sphingosine, CerNS24), lignoceric acid (LIG; 24:0), and cholesterol (Chol). X-ray diffraction experiments showed that the CerNH24-based samples form either a short lamellar phase (SLP, d ∼ 5.4 nm) or a medium lamellar phase (MLP, d = 10.63−10.78 nm) depending on the annealing conditions. The proposed molecular arrangement of the MLP based on extended Cer molecules also agreed with the relative neutron scattering length density profiles obtained from the neutron diffraction data. The presence of MLP increased the lipid film permeability to the lipophilic model permeant (indomethacin) relative to the CerNS24based control samples and the samples that had the same lipid composition but formed an SLP. Thus, the arrangement of lipids in various nanostructures is responsive to external conditions during sample preparation. This polymorphic behavior directly affects the barrier properties, which could also be (patho)physiologically relevant.

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Regional Biophysics Conference: RBC2018

Arsov

Koklic

2019

Eur Biophys J

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Application of small-angle neutron diffraction to the localization of general anesthetics in model membranes

Cited by 6 publications

References 42 publications

Cation–Zwitterionic Lipid Interactions Are Affected by the Lateral Area per Lipid

Cation–Zwitterionic Lipid Interactions Are Affected by the Lateral Area per Lipid

Polymorphism, Nanostructures, and Barrier Properties of Ceramide-Based Lipid Films

Regional Biophysics Conference: RBC2018

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