Fluorometric detection of the bilayer-to-hexagonal phase transition in liposomes

Hong, Keelung; Baldwin, Patricia A.; Allen, Theresa M.; Papahadjopoulos, Demetrios

doi:10.1021/bi00411a009

Cited by 70 publications

(43 citation statements)

References 23 publications

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“…Phase Transition and Phase Separation of Lipids-To measure the T H , the fluorescence intensity of NBD-PE incorporated into liposomes was measured as a function of temperature at 534 nm, with the excitation wavelength of 460 nm (24). The fluorescence emission spectra were recorded with a Shimazu RF-5301 PC spectrofluorometer equipped with a thermostated cuvette compartment.…”

Section: Methodsmentioning

confidence: 99%

Effects of Nonlamellar-prone Lipids on the ATPase Activity of SecA Bound to Model Membranes

Ahn

Kim

1998

Journal of Biological Chemistry

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The effect of nonlamellar-prone lipids, diacylglycerol (DG) and phosphatidylethanolamine (PE), on the ATPase activity of SecA was examined. When Escherichia coli PE of the standard vesicles composed of 60 mol% of this lipid and 40 mol% of dioleoylphosphatidylglycerol (DOPG) is gradually replaced with either dioleoylglycerol (DOG) or dioeloyl PE (DOPE), the ATPase activity of SecA present together increased appreciably. On the other hand, when E. coli PE of the standard vesicles was replaced with DOG analogs, the SecA ATPase activity decreased slightly, and when replaced with phosphatidylcholine the decrease in the ATPase activity was more appreciable. When DOPE or E. coli PE was added to PC vesicles, the SecA ATPase activity was enhanced only slightly, suggesting that the hexagonal II structure per se is not

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Section: Methodsmentioning

confidence: 99%

Effects of Nonlamellar-prone Lipids on the ATPase Activity of SecA Bound to Model Membranes

Ahn

Kim

1998

Journal of Biological Chemistry

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“…29 The polarization of the NBD moiety might be used as a measure of the membrane packing in that region. 30,31 When labeled vesicles were exposed to phenyltin compounds, the polarization was affected by DPhT more than by TPhT. There was no measurable effect from TTPhT.…”

Section: Discussionmentioning

confidence: 98%

Effect of phenyltin compounds on lipid bilayer organization

Langner

Gabrielska

Kleszczyńska

et al. 1998

Appl. Organometal. Chem.

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Phenyltin compounds are known to be biologically active. Their chemical structure suggests that they are likely to interact with the lipid fraction of cell membranes. Using fluorescence and NMR techniques, the effect of phenyltin compounds on selected regions of model lipid bilayers formed from phosphatidylcholine was studied. The polarization of N‐(7‐nitrobenz‐2‐oxa‐1,3‐diazol‐4‐yl) dipalmitoyl‐L‐phosphatidylethanolamine and desorption of praseodymium ions was used to probe the polar region, whereas the polarization of 1 ‐ (4 ‐ trimethylammoniumphenyl) ‐ 6 ‐ phenyl ‐ 1,3,5‐hexatriene p‐toluenesulfonate measured the hydrophobic core of the membrane. In addition, changes in the N‐(5‐fluoresceinthiocarbanoly)dipalmitoyl ‐ L ‐ α ‐ phosphatidyl ‐ ethanolamine fluorescence intensity indicated the amount of charge introduced by organotin compounds to the membrane surface. There were no relevant changes of measured parameters when tetraphenyltin was introduced to the vesicle suspension. Diphenyltin chloride causes changes of the hydrophobic region, whereas the triphenyltin chloride seems to adsorb in the headgroup region of the lipid bilayer. When the hemolytic activity of phenyltin compounds was measured, triphenyltin chloride was the most effective whereas diphenyltin chloride was much less effective. Tetraphenyltin causes little damage. Based on the presented data, a correlation between activity of those compounds to hemolysis (and toxicity) and the location of the compound within the lipid bilayer could be proposed. In order to inflict damage on the plasma membrane, the compound has to penetrate the lipid bilayer. Tetraphenyltin does not partition into the lipid fraction; therefore its destructive effect is negligible. The partition of the compound into the lipid phase is not sufficient enough, by itself, to change the structure of the lipid bilayer to a biologically relevant degree. The hemolytic potency seems to be dependent on the location of the compound within the lipid bilayer. Triphenyltin chloride which adsorbs on the surface of the membrane, causes a high level of hemolysis, whereas diphenyltin chloride, which penetrates much deeper, seems to have only limited potency. © 1998 John Wiley & Sons, Ltd.

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“…A transition from the lamellar to the hexagonal phase is accompanied by a drastic increase of the fluorescence quantum yield [22]. Fig.…”

Section: Nbd-ptdetn Fluorescencementioning

confidence: 92%

“…Ca2 [8, 19 -211. A fluorimetric detection of the bilayer-to-hexagonal phase transition in diluted membrane suspension has been introduced which allows the analysis of the transition kinetics [22]. A recent review summarizes the actual knowledge of the structure of the inverted hexagonal (HII) phase and of the non-lamellar phase transitions of lipids [23].…”

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confidence: 99%

Synergistic effects of Ca²⁺ and wheat germ agglutinin on the lamellar‐hexagonal (H_II) phase transition of glycophorin‐containing egg‐phosphatidylethanolamine membranes

Tampé

Galla

1991

European Journal of Biochemistry

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Glycophorin has been reconstituted into egg phosphatidylethanolamine (egg-PtdEtn) membranes. Stable vesicles were obtained at a molar ratio of 8 x of inserted protein/lipid. This macroscopic change from lipid aggregates to lipid vesicles was followed by density gradient centrifugation. Vesicles formed in the presence of protein enclose the dye calcein and are stable with time and temperature. Membrane aggregation does not occur, as was demonstrated by energy-transfer experiments. The phase transition from the fluid lamellar L, phase to the inverted hexagonal HII phase observed at 29" C in pure egg-PtdEtn membranes is suppressed and finally disappears in the presence of glycophorin. The transition enthalpy decreases linearly from AH = 4 kJ/mol in pure lipids to zero at a protein/lipid molar ratio of 1 : 1000. Ca2 [8, 19 -211. A fluorimetric detection of the bilayer-to-hexagonal phase transition in diluted membrane suspension has been introduced which allows the analysis of the transition kinetics [22]. A recent review summarizes the actual knowledge of the structure of the inverted hexagonal (HII) phase and of the non-lamellar phase transitions of lipids [23].In addition to the application of different experimental techniques, models were developed postulating two types of inverted micellar structures [24]. Spherical inverted micelles (lipid particles) sandwiched between the lipid monolayers of a bilayer membrane are opposed to inverted micellar intermediates which are transient intermediates within an interbilayer attachment site necessary for the process of membrane aggregation, membrane fusion or the lamellar-to-hexagonal (HII) phase transition [25,26]. Siegel states that inverted micellar intermediates formed at the interface of interacting bilayers may either (a) revert or (b) transform into an interlamellar attachment or (c) into a HII-phase precursor formed via coalescence of inverted micellar intermediates in a pearl-string fashion. Beside this monolayer-encapsulated HII tube, which is called a rod micellar intermediate, Siegel proposes a second type of intermediate [25]. The coalescence of inverted micellar intermediates may also lead to the formation of line defects which than elongate into structures consisting of two opposed halves of HII tubes. Formations of interlamellar attachments, rod micellar intermediates, as well as line defects, ILA, RMI as well as LD depends on the density of inverted micellar intermediates within the bilayer membrane. The formation of HII precusors is accompanied by intramembraneous lipid mixing and in vesicle systems by leakage of aqueous content.

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Fluorometric detection of the bilayer-to-hexagonal phase transition in liposomes

Cited by 70 publications

References 23 publications

Effects of Nonlamellar-prone Lipids on the ATPase Activity of SecA Bound to Model Membranes

Effects of Nonlamellar-prone Lipids on the ATPase Activity of SecA Bound to Model Membranes

Effect of phenyltin compounds on lipid bilayer organization

Synergistic effects of Ca²⁺ and wheat germ agglutinin on the lamellar‐hexagonal (H_II) phase transition of glycophorin‐containing egg‐phosphatidylethanolamine membranes

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Fluorometric detection of the bilayer-to-hexagonal phase transition in liposomes

Cited by 70 publications

References 23 publications

Effects of Nonlamellar-prone Lipids on the ATPase Activity of SecA Bound to Model Membranes

Effects of Nonlamellar-prone Lipids on the ATPase Activity of SecA Bound to Model Membranes

Effect of phenyltin compounds on lipid bilayer organization

Synergistic effects of Ca2+ and wheat germ agglutinin on the lamellar‐hexagonal (HII) phase transition of glycophorin‐containing egg‐phosphatidylethanolamine membranes

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Synergistic effects of Ca²⁺ and wheat germ agglutinin on the lamellar‐hexagonal (H_II) phase transition of glycophorin‐containing egg‐phosphatidylethanolamine membranes