A differential scanning calorimetric study of the thermotropic phase behavior of model membranes composed of phosphatidylcholines containing linear saturated fatty acyl chains

Lewis, Richard L.; Mak, Nanette; McElhaney, Ronald N.

doi:10.1021/bi00393a026

Cited by 339 publications

(304 citation statements)

References 36 publications

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“…As shown in Figs 3A-D, the main gel/liquid phase transition of the pure lipids was detected between -6°C and -1°C for LaulGroPCho, 20-24°C for Myr,GroPCho, 37-41 "C for PamZGroPCho and 42-55°C for Ste,GroPCho. These values are to be compared to the phase transition temperatures T,,, of -13°C to 0"C, 23-24"C, 41-42°C and 54-55°C previously reported for the same lipids and obtained using a large variety of techniques (Mabrey and Sturtevant, 1976;Huang et a1.,1982;Small, 2986;Lewis et al, 1987). Note that the L, -.…”

Section: The Probe Anthroyl-gropcho As a Detector Of The Gelhiquid Phmentioning

confidence: 85%

Hydrophobic mismatch and long‐range protein/lipid interactions in bacteriorhodopsin/phosphatidylcholine vesicles

Piknová

Perochon

Tocanne

1993

European Journal of Biochemistry

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Mismatch between the hydrophobic thicknesses of transmembrane proteins and the supporting lipid bilayer and its consequences on the lateral organization of lipids have been investigated with bacteriorhodopsin and phosphatidylcholine species with a variety of acyl-chain lengths. The purple membrane, from the bacterium Halobacteriuin halobium, was used and reconstituted with dilauroyl-(Lau,GroPCho), dimyristoyl-(Myr,GroPCho), dipalmitoyl-(Pam,GroPCho) and distearoyl-(Ste, GroPCho) glycerophosphocholine. The phase behaviour of the lipids was investigated at different temperatures and different protein/lipid molar ratios, by analyzing the fluorescence excitation spectra of the 1 -acyl-2-[ 8-(2-anthroyl)-octanoyl]-sn-glycero-3-phosphocholine probe, and by measuring the fluorescence depolarization of the 1,6-diphenyl-l,3,5-hexatriene probe. Data obtained with 1 -acyl-2-[8-(2-anthroyl)-oct~oyl]-sn-glycero-3-phosphocholine shows that bacteriorhodopsin produced positive or negative shifts in the phase transition temperature of the host lipids depending on the strength and sign of the mismatch between the lipid and protein hydrophobic thicknesses and also on the protein concentration and aggregation state in the lipid bilayer. In the region of high protein concentration (bacteriorhodopsidphosphatidylcholine molar ratios = 1 : 50) and despite the presence of the endogenous lipids, bacteriorhodopsin (hydrophobic length d, = 3.0 -3.1 nm) brought about a large upward shift in the phase-transition temperature of Lau,GroPCho (AT = 40 K, mean hydrophobic thickness d = 2.4 nm), and to a lesser extent of Myr,GroPCho (AT = 23 K, d = 2.8 nm), accounting for a strong rigidifying effect of the protein on these short-chain lipids. Bacteriorhodopsin had no influence on the phase properties of Pam,GroPCho (AT = 0 K, d 3.2 nm), a lipid whose mean hydrophobic thickness is similar to that of the protein. In contrast, the transition temperature of Ste,GroPCho was decreased (AT = -13 K, d = 3.7 nm), indicating a fluidifying effect of the protein on this long-chain lipid. Similar effects on the lipid acyl-chain order were observed in the region of high-protein dilution (bacteriorhodopsidphosphatidylcholine molar ratios < 1 : 500).In this region and for Lau,GroPCho, both the spectroscopic data and circular-dichroism spectra indicated that the protein was in the monomeric form. Phase diagrams, in temperature versus bacteriorhodopsin concentration, were constructed for Lau,GroPCho and Ste,GroPCho. On account of microscopic theoretical models and of the relative values of d, and d, these diagrams indicate a preference of the protein for those lipid molecules which are in the gel-ordered state in Lau2. GroPCho but in the liquid disordered state in Ste,GroPCho. The phase diagram of Lau,GroPCho was also analyzed using another theoretical approach based upon elastic models within the Landaude Gennes theory. This allowed for the estimation of the coherence length < which characterizes the distance over which the hydrophobic thickness of the lipid bilay...

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Section: The Probe Anthroyl-gropcho As a Detector Of The Gelhiquid Phmentioning

confidence: 85%

Hydrophobic mismatch and long‐range protein/lipid interactions in bacteriorhodopsin/phosphatidylcholine vesicles

Piknová

Perochon

Tocanne

1993

European Journal of Biochemistry

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“…In the absence of peptide, DMPC and DMPG MLVs exhibit two endothermic events on heating, i.e. a weakly energetic pretransition near 13°C (conversion of the ordered lamellar gel phase L␤Ј, with tilted hydrocarbon chains, to the ordered rippled gel phase P␤Ј) and a strongly energetic and highly cooperative main transition near 23°C (DMPG) or 24°C (DMPC) (conversion of the rippled gel phase to the fluid lamellar liquidcrystalline phase L␣) (35,36) (Fig. 5).…”

Section: Molecular Cloning and Identification Of Temporin-shf From Thmentioning

confidence: 99%

Temporin-SHf, a New Type of Phe-rich and Hydrophobic Ultrashort Antimicrobial Peptide

Abbassi¹,

Lequin

Piesse

et al. 2010

Journal of Biological Chemistry

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Because issues of cost and bioavailability have hampered the development of gene-encoded antimicrobial peptides to combat infectious diseases, short linear peptides with high microbial cell selectivity have been recently considered as antibiotic substitutes. A new type of short antimicrobial peptide, designated temporin-SHf, was isolated and cloned from the skin of the frog Pelophylax saharica. Temporin-SHf has a highly hydrophobic sequence (FFFLSRIFa) and possesses the highest percentage of Phe residues of any known peptide or protein. Moreover, it is the smallest natural linear antimicrobial peptide found to date, with only eight residues. Despite its small size and hydrophobicity, temporin-SHf has broad-spectrum microbicidal activity against Gram-positive and Gram-negative bacteria and yeasts, with no hemolytic activity. CD and NMR spectroscopy combined with restrained molecular dynamics calculations showed that the peptide adopts a well defined non-amphipathic ␣-helical structure from residue 3 to 8, when bound to zwitterionic dodecyl phosphocholine or anionic SDS micelles. Relaxation enhancement caused by paramagnetic probes showed that the peptide adopts nearly parallel orientations to the micelle surface and that the helical structure is stabilized by a compact hydrophobic core on one face that penetrates into the micelle interior. Differential scanning calorimetry on multilamellar vesicles combined with membrane permeabilization assays on bacterial cells indicated that temporin-SHf disrupts the acyl chain packing of anionic lipid bilayers, thereby triggering local cracks and microbial membrane disintegration through a detergent-like effect probably via the carpet mechanism. The short length, compositional simplicity, and broad-spectrum activity of temporin-SHf make it an attractive candidate to develop new antibiotic agents.

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“…These temperatures are in good agreement with the temperatures of the pretransition arising from the conversion from the lamellar gel (L ¢ ¤) phase to the ripple gel (P ¢ ¤) phase, and the main transition from the conversion from the P ¢ ¤ phase to the liquid crystalline (L ¡ ) phase, respectively. 6 At X er = 0.086, the small increase in max corresponding to the pretransition was not clearly observed, signifying that the pretransition was abolished in the binary bilayer containing such a concentration of ergosterol. A more accurate X er value for the abolition of the pretransition was determined by taking the results of the DSC measurements into account.…”

Section: ¹1mentioning

confidence: 95%

Thermotropic Phase Behavior of Binary Bilayer Membrane of Dipalmitoylphosphatidylcholine and Ergosterol

et al. 2012

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We investigated the phase behavior of a binary bilayer membrane of dipalmitoylphosphatidylcholine (DPPC) and ergosterol, using Prodan fluorescence spectroscopy and differential scanning calorimetry to construct a temperaturecomposition phase diagram. We found that several important features of the phase diagram can be explained by the superlattice view, on the basis of the hexagonal lattice, which suggests the presence of a molecular cluster composed of an ergosterol molecule and its six surrounding DPPC molecules above an ergosterol composition of ca. 0.15.Cholesterol is a major component of cell membranes of animals, and the effect of cholesterol on the thermotropic bilayer phase behavior of phospholipids has long been studied. Although the phase behavior of binary bilayers containing cholesterol has still not been completely established, many important features of the cholesterol effect have been revealed. For example, cholesterol induces phase separation within a phospholipid bilayer and also an intermediate state, the so-called liquid ordered (L o ) state, between the ordered (S o ) and disordered (L d ) states above a certain cholesterol content.1 These findings led to the proposal of the raft hypothesis, 2 which provides the model of the cell membrane that is most widely accepted today. On the other hand, it is well known that other kinds of sterols exist in cell membranes of plants and fungi. Ergosterol is a sterol found in yeast and fungal cell membranes, and its chemical structure is identical to that of cholesterol, except that ergosterol has an additional ethyl group at C-24 and two double bonds, between C-7 and C-8 and between C-22 and C-23. Ergosterol is generally thought to have the same functions as cholesterol in animal cell membranes. However, there are far fewer studies of ergosterol than of cholesterol and little is known about the effect of ergosterol on the phase behavior of phospholipid bilayers.3 In this study, we examined the phase behavior of a binary bilayer of dipalmitoylphosphatidylcholine (DPPC) and ergosterol by differential scanning calorimetry (DSC) and fluorescence spectroscopy using 6-propionyl-2-(dimethylamino)naphthalene (Prodan) as a polarity-sensitive membrane probe to construct a temperature composition phase diagram.A synthetic phospholipid, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, and (22E)-ergosta-5,7,22-trien-3¢-ol were purchased from Avanti Polar Lipids (Alabaster, AL) and SigmaAldrich Co. (St. Louis, MO), respectively, and used without further purification. A fluorescence probe Prodan was purchased from Molecular Probes Inc. (Eugene, OR). Water was distilled twice from dilute alkaline permanganate for use in the preparation of all the sample dispersions. Aqueous dispersions of DPPC vesicle particles and DPPCergosterol vesicle particles with different ergosterol compositions were prepared as follows. First, stock solutions of ergosterol/chloroform and Prodan/ ethanol were added to a weighed amount of DPPC powder and the mixed solution obtained was dried in a vacuu...

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A differential scanning calorimetric study of the thermotropic phase behavior of model membranes composed of phosphatidylcholines containing linear saturated fatty acyl chains

Cited by 339 publications

References 36 publications

Hydrophobic mismatch and long‐range protein/lipid interactions in bacteriorhodopsin/phosphatidylcholine vesicles

Hydrophobic mismatch and long‐range protein/lipid interactions in bacteriorhodopsin/phosphatidylcholine vesicles

Temporin-SHf, a New Type of Phe-rich and Hydrophobic Ultrashort Antimicrobial Peptide

Thermotropic Phase Behavior of Binary Bilayer Membrane of Dipalmitoylphosphatidylcholine and Ergosterol

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