A calorimetric and fluorescent probe study of the gel-liquid crystalline phase transition in small, single-lamellar dipalmitoylphosphatidylcholine vesicles

Suurkuusk, J.; Lentz, Barry R.; Barenholz, Y.; Biltonen, Rodney L.; Thompson, T. E.

doi:10.1021/bi00652a007

Cited by 474 publications

(268 citation statements)

References 25 publications

Supporting

Mentioning

236

Contrasting

Unclassified

Order By: Relevance

“…1,2-Dipalmitoyl-3-sn-phosphatidylcholine, prepared by the method of Cubero Robles and Van den Berg as described by Suurkuusk et al (6), was dissolved in spectral grade chloroform and stored at -20°u ntil used. Solvent was removed from a measured volume of solution at room temperature by evaporation.…”

Section: Methodsmentioning

confidence: 99%

“…These studies used a heat conduction-type differential scanning calorimeter with a precision of better than +25 ,ucal/degree (105 ,uJ/degree), as baseline noise, The details of the experimental procedure have been described (6). For pressure studies, a specially designed thick-walled stainless steel cell of approximately 0.4 ml volume was constructed.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Effect of anesthetics and pressure on the thermotropic behavior of multilamellar dipalmitoylphosphatidylcholine liposomes.

Mountcastle¹,

Biltonen²,

Halsey³

1978

Proc. Natl. Acad. Sci. U.S.A.

139

View full text Add to dashboard Cite

The effects of gaseous anesthetics and pressure on the thermotropic behavior of multilamellar dipalmitoylphosphatidylcholine liposomes were studied by using a highsensitivity differential scanning calorimeter. It was found that halothane and enflurane decreased the transition temperature and increased the width of the transition without affecting the enthalpy change for the main gel-to-liquid crystalline transition. This emonstrated that the anesthetics decreased the degree of cooperative interaction between phospholipid molecules within the bilayer. Increasing the pressure increased the transition temperature but did not affect the transition width or enthalpy change. However, the increase in pressure reversed the effect of anesthetic on both the transition temperature and transition width. It is sugested that an understanding of the effect of anesthetics on the degree of cooperative interaction between phospholipids may be a key to understanding anesthetic action.The physiological effect of inhalation anesthetics is likely a manifestation of the perturbation of membrane functions associated with synaptic transmission of nerve impulses. This conclusion is primarily based on the high degree of correlation between anesthetic potency and lipid solubility (1, 2). Although it is possible that the primary sites of the action of anesthetics are specific membrane proteins, an attractive alternative is that such action is the result of induced changes in the dynamic structure of the lipid matrix.Trudell and coworkers (3) have demonstrated that general anesthetics decrease the gel-to-liquid crystalline phase transition temperature of phospholipid bilayers and that this effect can be reversed by application of moderate pressures [-100 atmospheres (atm) (10 MPa)] to the system. This result is particularly intriguing because the physiological effect can also be reversed by moderate pressures (4). Recently, Trudell (5) developed a phenomenological theory of anesthesia based on the concept of lateral phase separation in the membrane. This theory focuses on the absolute increase in fluidity of the phospholipid matrix caused by anesthetics. It was suggested that, when phase separation no longer exists, membranes are less able to facilitate the protein conformational changes necessary for normal physiological function.In order to assess carefully the effect of the gaseous anesthetics on the thermotropic behavior of lipid bilayers, a detailed study was initiated using a highly sensitive differential scanning calorimeter. In addition, the influence of pressure on this behavior was ascertained by using a pressure cell adapted for this calorimeter. The results of this study show that the general anesthetics halothane (CF3CHBrCl) and enflurane (CHF2OCF2CHFCI) decrease the transition temperature without affecting the enthalpy change for the transition but that the degree of cooperative interaction between phospholipid molecules is decreased. Both these effects can be reversed by the application of moderate pressures. We there...

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Effect of anesthetics and pressure on the thermotropic behavior of multilamellar dipalmitoylphosphatidylcholine liposomes.

Mountcastle¹,

Biltonen²,

Halsey³

1978

Proc. Natl. Acad. Sci. U.S.A.

139

View full text Add to dashboard Cite

show abstract

“…Thus, the kinetics of transport processes are more complex due to multiple diffusion barriers and it is not easy to obtain a uniform-sized population of vesicles. These disadvantages are overcome by the use of small, unilamellar vesicles; however, the surface of these vesicles has a high degree of curvature which affects many of the physical properties of the phospholipid in the vesicles (8,9). One would then expect the large, unilamellar vesicles to resemble most closely biological membranes.…”

mentioning

confidence: 99%

Formation and properties of 1000-A-diameter, single-bilayer phospholipid vesicles.

Enoch¹,

Strittmatter²

1979

Proc. Natl. Acad. Sci. U.S.A.

216

View full text Add to dashboard Cite

Two methods are reported for the formation of large, uniform-sized phospholipid vesicles. (5) or ether injection (6). Vesicles may be formed with phospholipid mixtures, purified phospholipids, or synthetic phospholipids. The methods of preparation and the properties of such vesicles have recently been reviewed (1, 7). Although multilamellar liposomes are easy to prepare, they have been criticized as a model system for the study of membrane phenomena (1). Thus, the kinetics of transport processes are more complex due to multiple diffusion barriers and it is not easy to obtain a uniform-sized population of vesicles. These disadvantages are overcome by the use of small, unilamellar vesicles; however, the surface of these vesicles has a high degree of curvature which affects many of the physical properties of the phospholipid in the vesicles (8, 9). One would then expect the large, unilamellar vesicles to resemble most closely biological membranes. It was previously shown (4) that treatment of 1 mol of egg lecithin with 2 mol of bile salt followed by gel filtration to remove the bile salt results in the formation of a uniform population of single-bilayer vesicles having an average diameter of 300 A. We now report that the treatment of 1 mol of egg lecithin with 0.5 mol of bile salt results in the formation of a uniform population of single-bilayer vesicles having an average diameter of 1000 A. These preparations, which have a large internal volume and are free of multilamellar structures, may be useful in cases in which previous techniques (5, 6) cannot be applied.MATERIALS AND METHODS Egg phosphatidylcholine (10), sodium deoxycholate (11), cytochrome b5 heme peptide (12), the catalytic fragment of NADH-cytochrome b5 reductase (13) (pH 5) or 1% ammonium molybdate (pH 5). One drop of liposomes (30-100 ,uM phospholipid) was placed on a Formvar-coated grid and, after 30 sec, one drop of staining solution was added; 30 sec later, the solution was drained off with filter paper and the grid was allowed to air dry. The grids were examined in a Hitachi llE electron microscope operated at 75 kV. Vesicle diameters were measured on several electron micrographs covering different areas on a grid and then averaged from at least 400 measurements.Method I: Formation of Large Vesicles from Small, Preformed Vesicles. Small, uniform-sized egg lecithin vesicles were prepared as described (11). Any solute to be entrapped was added to the vesicle solution at this point and the vesicles were adjusted to 20 mM phospholipid. The solution was then warmed to 25°C and an aliquot of 250 mM sodium deoxycholate was rapidly added and mixed to give a final mixture containing a ratio of deoxycholate to phospholipid of 1:2. The large vesicles began to form almost immediately, as indicated by. the increase in the light scattering of the solution, a change from nearly clear for the small vesicles to a transparent opalescence for the large vesicles. Vesicle formation was complete within 5-10 min at 250C (vesicles could also be formed at 40C...

show abstract

“…Suurkuusk et al reported that calorimetric enthalpies of small vesicles made up of synthetic PC were smaller than those of large vesicles. 27) Malloy and Binford reported that about 50% DMPC were present in ultrasonicated centrifuged SUV. 22) Thus, the two peaks shown in Fig.…”

Section: )mentioning

confidence: 99%

“…9B). According to Suurkuusk et al,27) DMPC SUV containing small amounts of Na-chol aggregate and fuse into large vesicles. As shown in Figs.…”

Section: )mentioning

confidence: 99%

Physical Properties of Phosphatidylcholine Vesicles Containing Small Amount of Sodium Cholate and Consideration on the Initial Stage of Vesicle Solubilization.

Sun

Kashiwagi

Ueno

2002

CHEMICAL & PHARMACEUTICAL BULLETIN

View full text Add to dashboard Cite

Sodium cholate (Na-chol) is a physiological detergent. Its solubilizing properties are important in several fundamental biophysical and biochemical processes. This includes disintegration of biomembranes to mixed micelles, 1) reconstitution of membrane proteins and lipids to functional supramolecular structures (vesicles in most cases) 2,3) and preparation of homogeneous lipid vesicles of controlled sizes. 4,5) The vesicle destruction mechanism has been studied in connection with the reconstitution of membrane proteins after purification in detergent solutions. Concerning the disintegration from mixed vesicles to mixed micelles by Nachol, many studies have concentrated on the variation in morphology and properties of mixed aggregates.6,7) Consequently, the solubilization process of phosphatidylcholine (PC) vesicles is summarized as follows; addition of very small amounts of Na-chol to vesicles results in the partitioning of Na-chol between the water and lipid phases. At a further increased detergent concentration, vesicles containing a large amount of Na-chol are formed, whose behavior, such as fusion of small vesicles to larger ones, is found to be different from that of PC vesicles containing large amounts of nonionic detergents (i.e. octylglucoside).5) At a still further increased detergent concentration, the Na-chol-containing vesicles disintegrate into intermediate structures, and finally into mixed micelles. 8,9) As far as intermediate structures are concerned, structural changes from vesicles to perforated vesicles, to discoidal sheets, 10) or to rod-like structures 11) have been reported. As described above, the incorporation of Na-chol into vesicular membranes remarkably influences the structures and properties of PC vesicles. However, little is known about the effects of the incorporation of Na-chol on the behavior of membranes at a molecular level, although it is important for further detailed studies on the mechanism of vesicle disintegration. The present report deals with the influence of addition of small amounts (insufficient to destroy vesicles) of Na-chol on several physicochemical properties of PC small unilamellar vesicles (SUV). Similar to the previous reports, 12-14) ESR spectra of a spin label 12-doxylstearic acid (12-DS) are applied to monitor the variation in properties and structures of the mixed PC SUV. Differential scanning calorimetry (DSC) and z potentials measured with electrophoretic light scattering methods were also employed for observing the variation in the properties of PC SUV induced by Na-chol. The obtained results will be considered in connection with the initial stage of the solubilization of PC vesicular membranes. ExperimentalMaterials Phosphatidylcholine isolated from egg yolk (EPC) (purity approximately 98.8%) was purchased from Nihon Yushi (Tokyo, Japan). Sodium cholate and cholesterol of guaranteed degree were obtained from Nacalai Tesque (Kyoto, Japan). Synthetic dimyristoylphosphatidylcholine (DMPC) (purity ca. 99%) as well as 5-, 12-, and 16-DS were purchased from...

show abstract

A calorimetric and fluorescent probe study of the gel-liquid crystalline phase transition in small, single-lamellar dipalmitoylphosphatidylcholine vesicles

Cited by 474 publications

References 25 publications

Effect of anesthetics and pressure on the thermotropic behavior of multilamellar dipalmitoylphosphatidylcholine liposomes.

Effect of anesthetics and pressure on the thermotropic behavior of multilamellar dipalmitoylphosphatidylcholine liposomes.

Formation and properties of 1000-A-diameter, single-bilayer phospholipid vesicles.

Physical Properties of Phosphatidylcholine Vesicles Containing Small Amount of Sodium Cholate and Consideration on the Initial Stage of Vesicle Solubilization.

Contact Info

Product

Resources

About