Small angle X-ray scattering of microemulsions

Würz, U.

doi:10.1007/bfb0114186

Cited by 6 publications

(2 citation statements)

References 12 publications

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“…X-ray Diffraction. X-ray diffraction measurements were performed using a Kratky small-angle X-ray scattering apparatus with slit geometry [see Würz (1988)]. Compared with the range of scattering angles covered, the slit can be regarded as of infinite length, and the half-width of the beam (1.5 X 10"3Á-1) is negligible.…”

Section: Methodsmentioning

confidence: 99%

Structure of vitaminylated lipids in aqueous dispersion: X-ray diffraction and phosphorus-31 NMR studies of N-biotinylphosphatidylethanolamines

1993

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The structures of the phases formed in excess buffer (at pH 7.4) by a homologous series of saturated diacylphosphatidylethanolamines in which the headgroup is N-derivatized with biotin have been investigated for chain lengths of C(12:0) to C(20:0), using both 31P nuclear magnetic resonance (NMR) spectroscopy and small-angle X-ray diffraction. In 1 M NaCl, all lipids display 31P NMR spectra characteristic of a lamellar gel phase at low temperature. In the fluid phase, the lipids of C(12:0) and C(14:0) chain lengths display isotropic 31P NMR spectra, corresponding to aggregated phases with high surface curvature, whereas those with C(18:0) and C(20:0) chain lengths display sharp axial powder patterns characteristic of a lamellar (L alpha) phase. The lipid of intermediate C(16:0) chain length displays a more complex temperature dependence of the 31P NMR spectra in the fluid phase. The spectra convert from an axial powder pattern of unusually low chemical shift anisotropy to one characteristic of a fluid lamellar (L alpha) phase with increasing temperature. The small-angle X-ray diffraction patterns of the lipids in 1 M NaCl have lamellar repeat spacings in the gel phase which increase linearly with chain length and are consistently lower than those in the fluid phase [for chain lengths of C(16:0) to C(20:0)]. In addition, the gradient in long spacing with chain length in the gel phase is approximately half that expected for a gel phase with untilted, all-trans chains, indicating that the lipid chains are interdigitated in the gel phase (L beta i).(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Methodsmentioning

confidence: 99%

Structure of vitaminylated lipids in aqueous dispersion: X-ray diffraction and phosphorus-31 NMR studies of N-biotinylphosphatidylethanolamines

1993

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“…X-ray diffraction measurements were performed using a Kratky small-angle X-ray camera with a single-entrance slit of a width of 30 Am [19]. Compared with the range of scattering angles covered, the slit can be regarded as of infinite length, and the half-width of the beam (1.5 Â 10 À 3 Å À 1 ) is negligible.…”

Section: X-ray Diffractionmentioning

confidence: 99%

Miscibility and phase behaviour of binary mixtures of N-palmitoylethanolamine and dipalmitoylphosphatidylcholine

Swamy

Ramakrishnan

Marsh

et al. 2003

Biochimica et Biophysica Acta (BBA) - Biomembranes

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The content of N-acylethanolamines (NAEs) increases dramatically in cell membranes when the parent organism is subjected to injury or stress. This increase has been attributed to stress-combating mechanisms of the organism. In this study, a binary phase diagram of hydrated mixtures of N-palmitoylethanolamine (NP-E)--an endogenous ligand for the peripheral cannabinoid receptor (CB-2)--with dipalmitoylphosphatidylcholine (DPPC) is established by high-sensitivity differential scanning calorimetry (DSC). The structures of the phases involved were determined by using 31P-NMR spectroscopy and low-angle X-ray scattering. DSC studies show that NP-E and DPPC mix well in the composition range DPPC/NP-E=100:0 to 40:60 (mol/mol). At higher contents of NP-E, phase separation is indicated by the presence of additional transitions in the thermograms. Characterization of the structures formed by the mixtures with 31P-NMR shows that, up to 80 mol% NP-E, DPPC remains in the lamellar phase. The low-angle X-ray diffraction data are also consistent with a lamellar gel-phase structure for DPPC/NP-E mixtures up to 60 mol% NP-E. Above 70 mol% NP-E, NP-E phase separates in the gel-phase region, while complete miscibility is observed in the fluid phase. These results provide a structural basis for understanding the membrane interactions of NAEs, which is necessary for understanding the mechanism of their putative stress-combating role in the parent organisms.

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