.ALPHA.-Tocopherol-induced hexagonal HII phase formation in egg yolk phosphatidylcholine membranes.

Nakajima, Kazuo; Utsumi, Hideo; Kazama, Masayoshi; Hamada, Akira

doi:10.1248/cpb.38.1

Cited by 19 publications

(9 citation statements)

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“…The 20 mol% value is very probably related to the limited solubility of α-Toc in phospholipid bilayers, whereas the disintegration of the membrane indicates a rapid change in the hydrophyllic-lipophyllic balance, bringing about the formation of non-lamellar structures. The formation of hexagonal H II or reversed cubic phases due to incorporated α-Toc was observed in DPPC or DPPE membranes [10,[40][41][42]. Microscopic and particle size measurements indicate that the presence of tocopherol with a molar ratio above 0.2 resulted in the effective formation and stabilization of submicrometer size vesicles.…”

Section: Discussionmentioning

confidence: 99%

Spectroscopic studies of D-α-tocopherol concentration-induced transformation in egg phosphatidylcholne vesicles

Dwiecki¹,

Górnaś²,

Wilk

et al. 2007

Cellular and Molecular Biology Letters

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Abstract:The effects of embedding up to 60 mol% of α-tocopherol (α-Toc) on the morphology and structure of the egg phosphatidylcholine (PC) membrane were studied using spectroscopic techniques. The resulting vesicles were subjected to turbidometric and dynamic light scattering measurements to evaluate their size distribution. The α-Toc intrinsic fluorescence and its quenching was used to estimate the tocopherol position in the membrane. Optical microscopy was used to visualize morphological changes in the vesicles during the inclusion of tocopherol into the 2 mg/ml PC membrane. The incorporation of up to 15 mol% of tocopherol molecules into PC vesicles is accompanied by a linear increase in the fluorescence intensity and the simultaneous formation of larger, multilamellar vesicles. Increasing the tocopherol concentration above 20 mol% induced structural and morphological changes leading to the disappearance of micrometer-sized vesicles and the formation of small unilamellar vesicles of size ranging from 30 to 120 nm, mixed micelles and non-lamellar structures.

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Section: Discussionmentioning

confidence: 99%

Spectroscopic studies of D-α-tocopherol concentration-induced transformation in egg phosphatidylcholne vesicles

Dwiecki¹,

Górnaś²,

Wilk

et al. 2007

Cellular and Molecular Biology Letters

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“…Collapse of a mixed monolayer depends not only upon the lipid-lipid interactions and miscibility in the monolayer but also upon those in the bulk lipid phases separated out (1 1-15 ). Diglycerides and a-tocopherol have large solubilities in the PC bilayers and the mixtures with PC form nonbilayer-phases besides the bilayers ( 17,18). Triglycerides and phospholipids have limited mutual solubilities in the bulk phases (TG liquid and phospholipid bilayers).…”

Section: Average Area Per Molecule Of Eutectic Monolayermentioning

confidence: 99%

Eutectic mixed monolayers in equilibrium with phospholipid-bilayers and triolein-liquid phase

Handa

Saito

Miyajima

1993

Biophysical Journal

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Triolein (TO) and phospholipids (egg yolk phosphatidylcholine, egg yolk phosphatidylethanolamine, and bovine brain phosphatidylserine) had low mutual solubilities and separated into the TO-liquid phase and phospholipid-bilayers. Spreading pressures of the TO-phospholipid mixture (i.e., surface pressures of the mixed monolayer in equilibrium with the phase-separating lipid mixture) at the air/saline interface were independent of the lipid composition. On the other hand, collapse pressures of the mixed monolayer of TO and phospholipid (i.e., surface pressures of the mixed monolayer in equilibrium with the TO-liquid phase) at the interface changed with the monolayer composition and were lower than the spreading pressure. The experimental data indicated the spreading and collapse pressures as offering a phase diagram for the presence of equilibrium between the mixed monolayer, the phospholipid-bilayers and the TO-liquid phase. The diagram showed that TO and the phospholipids were miscible in the mixed monolayer, forming an eutectic mixed monolayer. When the mixed monolayer initially had the eutectic composition, no collapse of the monolayer was detected until the surface pressure reached the value of the spreading pressure. No specific complex between TO and the phospholipid is required to explain the stability and collapse of the mixed monolayers. The bulk immiscibility of the lipids elucidated by the spreading pressure-measurements, immediately leads to the phase behaviors observed.

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“…Neutral lipids such as α‐tocopherol and phosphatidylcholine are miscible in the bulk phase and form a bilayer and hexagonal (H II ) phases [22]. E5531, EC or SM and DPPC are also miscible in the bulk phase and we investigated the phase structure of E5531/DPPC, EC/DPPC and SM/DPPC mixtures.…”

Section: Resultsmentioning

confidence: 99%

The effect of the lipid A analog E5531 on phospholipid membrane properties

1998

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In order to determine the effect of the lipid A analog, E5531, on phospholipid membranes, we used dipalmitoylphosphatidylcholine (DPPC) and investigated the physicochemical interaction between E5531 and DPPC membranes. E5531 and DPPC are miscible in the bulk phase at 25³C. Within the E5531 mole fraction range (X iSSQI ) of 0^0.5, E5531 decreased the zeta potentials of DPPC membranes but did not change the size of the DPPC liposomes. E5531/DPPC mixtures formed liposome-like structures. E5531 increased the fluidity of the DPPC membrane and decreased pyrene diffusion in the membrane. E5531 decreased the phase transition temperature and the cooperative interactions between DPPC molecules. These effects of E5531 on phospholipid membranes were different from those of lipid A from Escherichia coli and Salmonella minnesota.z 1998 Federation of European Biochemical Societies.

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.ALPHA.-Tocopherol-induced hexagonal HII phase formation in egg yolk phosphatidylcholine membranes.

Cited by 19 publications

References 0 publications

Spectroscopic studies of D-α-tocopherol concentration-induced transformation in egg phosphatidylcholne vesicles

Spectroscopic studies of D-α-tocopherol concentration-induced transformation in egg phosphatidylcholne vesicles

Eutectic mixed monolayers in equilibrium with phospholipid-bilayers and triolein-liquid phase

The effect of the lipid A analog E5531 on phospholipid membrane properties

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