Determination of n-alkane partitioning within phosphatidylethanolamine Lα/HII phases

Ramos, Adrian Paz; Doroudgar, Mahmoudreza; Lafleur, Michel

doi:10.1016/j.bbamem.2020.183201

Cited by 5 publications

(5 citation statements)

References 25 publications

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“…Similar observations have been made by Sjoelund et al, 47 who showed that water content has a noticeable effect on the formation of inverse hexagonal phases in different PC lipids and mentioned that adding C20 to DOPC resulted in the appearance of an isotropic component in the phosphorus spectra. Paz Ramos et al 33 also investigated the effect of alkanes on the L α -to-H II phase transition in PE lipids and observed a small isotropic lipid phase coexisting with the inverse-hexagonal phase. 31 P spectra displaying isotropic components are typically observed in sonicated lipid suspensions consisting of small vesicles.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The most recent and detailed studies on phospholipid/ n -alkane systems were motivated by the n -alkanes’ simple chemical structure and the ease with which their hydrophobic chain length can be varied, making these molecules an ideal model for fundamental investigations of the effect of linear hydrophobic chains on phospholipid bilayers. − …”

Section: Introductionmentioning

confidence: 99%

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Filling the Gap with Long n-Alkanes: Incorporation of C20 and C30 into Phospholipid Membranes

et al. 2022

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Investigating how hydrophobic molecules mix with phospholipid bilayers and how they affect membrane properties is commonplace in biophysics. Despite this, a molecular-level empirical description of a membrane model as simple as a phospholipid bilayer with long linear hydrophobic chains incorporated is still missing. Here, we present an unprecedented molecular characterization of the incorporation of two long n-alkanes, n-eicosane (C20) and n-triacontane (C30) with 20 and 30 carbons, respectively, in phosphatidylcholine (PC) bilayers using a combination of experimental techniques ( 2 H NMR, 31 P NMR, 1 H− 13 C dipolar recoupling solid-state NMR, X-ray scattering, and cryogenic electron microscopy) and atomistic molecular dynamics (MD) simulations. At low hydration, deuterated C20 and C30 yield 2 H NMR spectra evidencing anisotropic-motion, which demonstrates their miscibility in PC membranes up to a critical alkane-to-acyl-chain volume fraction, ϕ c . The acquired 2 H NMR spectra of C20 and C30 have notably different lineshapes. At low alkane volume fractions below ϕ c , CHARMM36 MD simulations predict such 2 H NMR spectra qualitatively and thus enable an atomistic-level interpretation of the spectra. Above ϕ c , the 2 H NMR lineshapes become characteristic of motions in the intermediate-regime that, together with the MD simulation results, suggest the onset of immiscibility between the alkane molecules and the acyl chains. For all the systems investigated, the phospholipid molecular structure is unperturbed by the presence of the alkanes. However, at conditions of excess hydration and at surprisingly low alkane fractions below ϕ c , a peak characteristic of isotropic motion is observed in both the 2 H spectra of the alkanes and 31 P spectra of the phospholipids, strongly indicating that the incorporation of the alkanes induces a reduction on the average radius of the lipid vesicles.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Filling the Gap with Long n-Alkanes: Incorporation of C20 and C30 into Phospholipid Membranes

et al. 2022

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“…The outer shoulders of the simulated spectrum are much more prominent than in the experimental spectra. Figure S3 indicates that this is because the spectra in Figure 2b were acquired using a too short recycle delay of 1 s. While such a short delay is suitable for liquid n-alkanes [63,64], it is clearly insufficient for the higher quadrupolar couplings of the solid methylene groups [50]. However, since the crystalline component can still be identified using the short recycle delay, and long recycle delays increase the measurement time beyond what is practical, we continued using a recycle delay of 1 s in this work.…”

Section: C30 Crystallizes Inside Dmpc and Popc Membranesmentioning

confidence: 99%

Crystallization of n-alkanes under anisotropic nano-confinement in lipid bilayers

Wurl,

Ott,

Schwieger

et al. 2023

Preprint

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Understanding crystallization behaviour is integral to the design of pharmaceutical compounds for which the pharmacological properties depend on the crystal forms achieved. Very often, these crystals are based on hydrophobic molecules. One method for delivering crystal-forming hydrophobic drugs is by means of lipid nanoparticle carriers. However, so far, a characterization of the potential crystallization of fully hydrophobic molecules in a lipid environment has never been reported. In this work we investigate the crystallization behaviour of two model hydrophobic chains, n-eicosane (C20) and n-triacontane (C30), in phospholipid bilayers. We combine static 2H nuclear magnetic resonance (NMR) spectroscopy and differential scanning calorimetry (DSC) and show that C30 can indeed crystallize inside DMPC and POPC bilayers. The phase transition temperatures of C30 are slightly reduced inside DMPC, and rotator phase formation becomes a two-step process: Pre-organized n-alkane chains assemble in rotator-phase crystallites just as fast as bulk C30, but further addition of molecules is notably slower. Under the same isothermal conditions, different crystal forms can be obtained by crystallization in the membrane and in bulk. In excess water conditions, homogeneous nucleation of C30 is observed. The initial anisotropic molecular arrangement of C30 molecules in the membrane is readily re-covered upon reheating, showing reversibility. The shorter C20 molecules on the other hand become trapped in the DMPC membrane gel-phase upon cooling and do not crystallize. This work marks the first observation of the crystallization of hydrophobic chains inside a lipid bilayer environment. As such, it defines a fundamental starting point for studying the crystallization characteristics of various hydrophobic molecules in lipid membranes.

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“…[3][4][5][6] HIE of C(sp 3 )À H bonds is also relevant for the decontamination of tritium-containing radioactive waste oils from nuclear facilities, [7][8][9][10][11] or for the deuteration of organic materials, [12][13][14] for instance to increase the performances of OLEDs. [15][16][17][18][19] Besides, perdeuterated alkanes are useful as solvents and probes for NMR studies, [20] as analytical standards for improved GC/MS data analysis, [21] and have received attention to prevent counterfeiting, for example to identify illegal fuels. [22] Several homogeneous catalysts have been developed for H/D exchange reactions of C(sp 2 )À H bonds, [1,2,[23][24][25][26][27] with great success.…”

Section: Introductionmentioning

confidence: 99%

Highly Selective and Efficient Perdeuteration of n‐Pentane via H/D Exchange Catalyzed by a Silica‐Supported Hafnium‐Iridium Bimetallic Complex

Pichugov,

Escomel,

Lassalle

et al. 2024

Angewandte Chemie

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A Surface OrganoMetallic Chemistry (SOMC) approach is used to prepare a novel hafnium‐iridium catalyst immobilized on silica, HfIr/SiO2, featuring well‐defined [≡SiOHf(CH2tBu)2(μ‐H)3IrCp*] surface sites. Unlike the monometallic analogous materials Hf/SiO2 and Ir/SiO2, which promote n‐pentane deuterogenolysis through C‐C bond scission, we demonstrate that under the same experimental conditions (1 bar D2, 250°C, 3h, 0.5 mol%), the heterobimetallic catalyst HfIr/SiO2 is highly efficient and selective for the perdeuteration of alkanes with D2, exemplified on n‐pentane, without substantial deuterogenolysis (<2% at 95% conversion). Furthermore this HfIr/SiO2 catalyst is robust and can be re‐used several times without evidence of decomposition. This represents substantial advance in catalytic H/D isotope exchange (HIE) reactions of C(sp3)‐H bonds.

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Determination of n-alkane partitioning within phosphatidylethanolamine Lα/HII phases

Cited by 5 publications

References 25 publications

Filling the Gap with Long n-Alkanes: Incorporation of C20 and C30 into Phospholipid Membranes

Filling the Gap with Long n-Alkanes: Incorporation of C20 and C30 into Phospholipid Membranes

Crystallization of n-alkanes under anisotropic nano-confinement in lipid bilayers

Highly Selective and Efficient Perdeuteration of n‐Pentane via H/D Exchange Catalyzed by a Silica‐Supported Hafnium‐Iridium Bimetallic Complex

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