1,2-Dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) divalent cation complexes: an X-ray scattering and freeze-fracture electron microscopy study

Garidel, Patrick; Förster, Günter; Richter, Walter; Kunst, Beno H.; Rapp, Gert; Blume, Alfred

doi:10.1039/b003276j

Cited by 23 publications

(15 citation statements)

References 47 publications

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“…For negatively charged single phospholipid bilayers, it is well known that the strong binding of Ca 2+ ions to the phosphate group such as in phosphatidylglycerols (PGs) and phosphatidlyserines (PSs) is entropy driven and causes a dehydration of the membrane (a decrease in a 0 ). Moreover, a condensing effect reflected by a tighter packing of the fatty acyl chains is observed [32] – [34] , [70] , [81] – [83] .…”

Section: Resultsmentioning

confidence: 96%

Calcium Triggered Lα-H2 Phase Transition Monitored by Combined Rapid Mixing and Time-Resolved Synchrotron SAXS

et al. 2008

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BackgroundAwad et al. [1] reported on the Ca2+-induced transitions of dioleoyl-phosphatidylglycerol (DOPG)/monoolein (MO) vesicles to bicontinuous cubic phases at equilibrium conditions. In the present study, the combination of rapid mixing and time-resolved synchrotron small-angle X-ray scattering (SAXS) was applied for the in-situ investigations of fast structural transitions of diluted DOPG/MO vesicles into well-ordered nanostructures by the addition of low concentrated Ca2+ solutions.Methodology/Principal FindingsUnder static conditions and the in absence of the divalent cations, the DOPG/MO system forms large vesicles composed of weakly correlated bilayers with a d-spacing of ∼140 Å (Lα-phase). The utilization of a stopped-flow apparatus allowed mixing these DOPG/MO vesicles with a solution of Ca2+ ions within 10 milliseconds (ms). In such a way the dynamics of negatively charged PG to divalent cation interactions, and the kinetics of the induced structural transitions were studied. Ca2+ ions have a very strong impact on the lipidic nanostructures. Intriguingly, already at low salt concentrations (DOPG/Ca2+>2), Ca2+ ions trigger the transformation from bilayers to monolayer nanotubes (inverted hexagonal phase, H2). Our results reveal that a binding ratio of 1 Ca2+ per 8 DOPG is sufficient for the formation of the H2 phase. At 50°C a direct transition from the vesicles to the H2 phase was observed, whereas at ambient temperature (20°C) a short lived intermediate phase (possibly the cubic Pn3m phase) coexisting with the H2 phase was detected.Conclusions/SignificanceThe strong binding of the divalent cations to the negatively charged DOPG molecules enhances the negative spontaneous curvature of the monolayers and causes a rapid collapsing of the vesicles. The rapid loss of the bilayer stability and the reorganization of the lipid molecules within ms support the argument that the transition mechanism is based on a leaky fusion of the vesicles.

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Section: Resultsmentioning

confidence: 96%

Calcium Triggered Lα-H2 Phase Transition Monitored by Combined Rapid Mixing and Time-Resolved Synchrotron SAXS

et al. 2008

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“…For graphical presentation of the temperature dependent X-ray data, a contour plot is used (Garidel et al, 2000), in which the scattering intensity is plotted as a height profile versus the reciprocal spacing and the temperature program. The scattering intensities were scaled in four different windows in order to intensify the reflections with a lower intensity in the wide angle region besides the strongest reflections.…”

Section: X-ray Diffractionmentioning

confidence: 99%

Hydration properties of N-(α-hydroxyacyl)-sphingosine: X-ray powder diffraction and FT–Raman spectroscopic studies

Raudenkolb

Wartewig²,

Brezesinski

et al. 2005

Chemistry and Physics of Lipids

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“…For graphical presentation of the temperature dependent X-ray data a contour plot was used (Garidel et al, 2000), in which the scattering intensity is plotted as a height profile versus the reciprocal spacing and the temperature program. The scattering intensities were scaled in four different windows in order to intensify the reflections with a lower intensity in the wide angle region besides the strongest reflections.…”

Section: X-ray Diffractionmentioning

confidence: 99%

Polymorphism of ceramide 6: a vibrational spectroscopic and X-ray powder diffraction investigation of the diastereomers of N-(α-hydroxyoctadecanoyl)-phytosphingosine

Raudenkolb¹,

Wartewig²,

Neubert³

2005

Chemistry and Physics of Lipids

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1,2-Dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) divalent cation complexes: an X-ray scattering and freeze-fracture electron microscopy study

Cited by 23 publications

References 47 publications

Calcium Triggered Lα-H2 Phase Transition Monitored by Combined Rapid Mixing and Time-Resolved Synchrotron SAXS

Calcium Triggered Lα-H2 Phase Transition Monitored by Combined Rapid Mixing and Time-Resolved Synchrotron SAXS

Hydration properties of N-(α-hydroxyacyl)-sphingosine: X-ray powder diffraction and FT–Raman spectroscopic studies

Polymorphism of ceramide 6: a vibrational spectroscopic and X-ray powder diffraction investigation of the diastereomers of N-(α-hydroxyoctadecanoyl)-phytosphingosine

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