Phase transition from a gel to a fluid phase of cubic symmetry in dimyristoylphosphatidylcholine/myristic acid (1:2, mol/mol) bilayers

Heimburg, Thomas; Ryba, Nicholas J. P.; Würz, U.; Marsh, Derek

doi:10.1016/0005-2736(90)90192-q

Cited by 30 publications

(12 citation statements)

References 19 publications

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“…Of the many examples of cubic phases formed by lipidwater dispersions (Lindblom and Rilfors, 1989) the Im3m cubic phase has been observed in a fully hydrated dispersion of dimyristoylphosphatidylcholine-myristic acid (1:2; mol/ mol) (Seddon et al, 1990b). A Pn3m cubic phase has also been reported to occur in this mixture (Heimburg et al, 1990). The bicontinuous inverted cubic phases of Im3m and Pn3m generally appear as intermediate phases between the smectic mesophase and HII structure in lipid-water systems (Seddon, 1990b;Lindblom and Rilfors, 1989).…”

Section: Resultsmentioning

confidence: 96%

Cubic phases in hydrated 1:1 and 1:2 dipalmitoylphosphatidylcholine-dipalmitoylglycerol mixtures

Takahashi¹,

Hatta²,

Quinn³

1996

Biophysical Journal

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The structures of fully hydrated 1:1 and 1:2 (mol/mol) dipalmitoylphosphatidylcholine (DPPC)-dipalmitoylglycerol (DPG) mixtures were studied by means of small-angle x-ray diffraction. The x-ray diffraction pattern of the 1:1 (mol/mol) DPPC-DPG mixture at 65 degrees C contains three reflections with spacings in the ratio of 1:1/ square root of 2:1/ square root of 3 in addition to reflections of an inverted hexagonal (H11) phase. A possible interpretation of this result is that a cubic phase of the body-centered space group lm3m, with a lattice constant of 23.1 +/- 0.6 nm, is formed. This cubic phase appears at intermediate temperatures between the lamellar and the H11 phases. The 1:2 (mol/mol) DPPC-DPG mixture gives an x-ray diffraction pattern at temperatures higher than the lamellar-to-H11 transition containing a number of reflections that index a cubic phase structure. The space group of the cubic phase was assigned a face-centered group Fd3m with a lattice constant of 16.3 +/- 0.1 nm at 82 degrees C. The possible role of cubic phases in membrane phenomena such as transmembrane signal transduction and fusion is discussed.

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Section: Resultsmentioning

confidence: 96%

Cubic phases in hydrated 1:1 and 1:2 dipalmitoylphosphatidylcholine-dipalmitoylglycerol mixtures

Takahashi¹,

Hatta²,

Quinn³

1996

Biophysical Journal

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“…The reversible conversion to the H n phase at higher temperature further supports the assignment to a cubic phase. Very recent X-ray diffraction measurements have identified this phase as one with the cubic space group Pn3m or possibly Im3m [22,27]. Fig.…”

Section: Resultsmentioning

confidence: 98%

Spin label ESR and 31P-NMR studies of the cubic and inverted hexagonal phases of dimyristoylphosphatidylcholine/myristic acid (1:2, mol/mol) mixtures

Krishna

Marsh

1990

Biochimica et Biophysica Acta (BBA) - Biomembranes

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The thermotropic phase behaviour and chain dynamics of the dimyristoylphosphatidylcholine/myristic acid (1:2, mol/mol) mixture at pH 4.0 have been studied with 31P-NMR and spin-label ESR. Broadline proton-dipolar decoupled 31P-NMR spectra show that the system undergoes a transition from a lamellar phase to a non-lamellar phase at 47 degrees C. The 31P-NMR spectrum collapses, from a lamellar powder pattern with apparent chemical shift anisotropy delta sigma = -38 ppm below 47 degrees C, to an isotropic spectrum with superimposed hexagonal powder pattern of delta sigma = +13 ppm above 47 degrees C. With increasing temperature, the hexagonal component grows at the expense of the isotropic component, finally transforming to a single hexagonal phase at approximately 70 degrees C. The ESR spectra from both fatty acid and phosphatidylcholine probes spin-labelled in the hydrocarbon chain have been used to study the ordering and mobility of the lipid chains through the lamellar-non lamellar transition. An abrupt increase in the chain mobility observed at approx. 47 degrees C demonstrates that the lamellar-non lamellar phase transition coincides with chain melting. The apparent order parameter and polarity profiles, deduced from the ESR spectra of 11 different chain-labelled positional isomers, demonstrate flexibility and polarity gradients characteristic of a lyotropic liquid crystalline phase. The temperature dependence of the order parameters does not show any changes in the fluid phase, indicating that the conversion from the isotropic (cubic) phase to the inverted hexagonal phase is not accompanied by large changes in chain order. A comparison of the apparent order parameters and polarity profiles of the phosphatidylcholine and fatty acid spin labels indicates that the fatty acid spin labels are intercalated approximately one CH2 unit more deeply in the hydrocarbon region than are the positionally isomeric phosphatidylcholine spin labels.

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“…They have not been established in detail and, in addition, the existence of intervening phases, e.g., ofthe cubic type (cf. Heimburg et al, 1990), cannot be excluded. The gel or solid phases of all three regions in the phase diagram are of lamellar structure, as is indicated by both 31P NMR and x-ray diffraction.…”

Section: Binary Phase Diagrammentioning

confidence: 99%

Binary phase diagram of hydrated dimyristoylglycerol-dimyristoylphosphatidylcholine mixtures

Heimburg

Würz²,

Marsh

1992

Biophysical Journal

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The thermotropic phase behavior of binary mixtures of dimyristoylphosphatidylcholine with dimyristoyl glycerol (DMPC-DMG) has been studied in aqueous dispersion by using differential scanning calorimetry and spin label electron spin resonance spectroscopy. Phase identifications have been made by means of (31)P nuclear magnetic resonance spectroscopy and x-ray diffraction. The binary phase diagram of DMPC-DMG mixtures displays three regions corresponding to the existence of compounds (C1 and C2, respectively) with approximately 1:1 and 1:2 mol/mol DMPC:DMG stoichiometries. The first region displays immiscibility between DMPC and C1 in the low temperature lamellar phase and miscibility of the components in the fluid phase that is lamellar. The second region displays immiscibility between C1 and C2 in the low temperature phase that is lamellar, whereas the fluid phase is of the inverted hexagonal type (H(II)). The third region displays immiscibility between C2 and DMG in the low temperature phase that is lamellar, whereas the fluid phase is isotropic. The presence of immiscible DMG in the low temperature phase of the third region is indicated by hysteresis in the temperature scans corresponding to conversion between the stable and metastable crystalline polymorphs. Analysis of the first region of the phase diagram using regular solution theory further demonstrates the existence of a DMPC:DMG complex with approximately 1:1 stoichiometry and provides parameters for the nonideality of mixing in the fluid phase.

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Phase transition from a gel to a fluid phase of cubic symmetry in dimyristoylphosphatidylcholine/myristic acid (1:2, mol/mol) bilayers

Cited by 30 publications

References 19 publications

Cubic phases in hydrated 1:1 and 1:2 dipalmitoylphosphatidylcholine-dipalmitoylglycerol mixtures

Cubic phases in hydrated 1:1 and 1:2 dipalmitoylphosphatidylcholine-dipalmitoylglycerol mixtures

Spin label ESR and 31P-NMR studies of the cubic and inverted hexagonal phases of dimyristoylphosphatidylcholine/myristic acid (1:2, mol/mol) mixtures

Binary phase diagram of hydrated dimyristoylglycerol-dimyristoylphosphatidylcholine mixtures

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