The function of sterols in membranes

Demel, R.A.; Kruyff, B. De

doi:10.1016/0304-4157(76)90008-3

Cited by 1,272 publications

(518 citation statements)

References 122 publications

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“…Cholesteryl (2'-hydroxy)-3-ethyl ether having a second oxygen function which is two carbon atoms separated from the ether oxygen at the cholesterol 3-position, has a high interacial stability and a cholesterol like effect both in the liquid-crystalline and gel state of the membrane. The results support the idea that no direct hydrogen bridge formation between phospholipid and sterol is required; hydrogen bonds with the bound water system still seem most plausible [7].…”

Section: Discussionsupporting

confidence: 81%

“…Long chain cholesteryl ester derivatives as cholesteryl oleate from hardly monomolecular layers in a pure form [29]. These observations have led previously to the assumption that a 3fl-hydroxyl group is essential for membrane sterols [7].…”

Section: Discussionmentioning

confidence: 99%

“…Differential scanning calorimetry measurements have shown that cholesterol has a liquifying effect, this means, decreases the chain order in the gel state [6]. These effects of cholesterol have led to the concept that cholesterol can introduce an intermediate gel state [7]. Both model membrane experiments and studies on biological membranes have revealed that the sterol structure is of critical importance for the sterol phospholipid interaction [8,9].…”

Section: Introductionmentioning

confidence: 99%

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The effect of the sterol oxygen function on the interaction with phospholipids

Demel

Lala

Kumari

et al. 1984

Biochimica et Biophysica Acta (BBA) - Biomembranes

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The effect of cholesteryi ethers (namely cholesteryl methyl ether, cholesteryi ethyl ether, cholesteryl n-propyl ether, cholesteryi isopropyl ether, cholesteryi butyl ether, cholesteryl methoxymethyl ether, cholesteryl (2'-hydroxy)-3-ethyl ether) and cholesteryl ester (namely cholesteryi acetate) is tested on the interaction with phosphatidylcholines in liquid-crystalline and crystalline state. The interfacial properties of sterols are tested at the air-water interface. The cholesteryl ethers show a reduced interracial stability with increasing hydrophobicity of the ether-linked moiety. The interaction between the sterol derivatives and phospholipids in mixed monolayers is indicated by measuring the deviation from the simple addivity rule (condensing effect). An interaction is found only for cholesteryl (2'-hydroxy)-3-ethyl ether, cholesteryl methyl ether and cholesteryl ethyl ether. These sterols also reduce the glucose permeability of liposomal membranes in this order. In this respect cholesteryl (2'-hydroxy)-3-ethyl ether is as effective as cholesterol. Cholesteryl methyl ether and cholesteryl ethyl ether show 62 and 33 percent of the effect observed with cholesterol. The effect of the sterol derivatives on the gel-to-liquid-crystalline phase transition of dipalmitoylphosphatidylcholine is measured by differential scanning calorimetry. Cholesteryl methyl ether, cholesteryl ethyl ether, and cholesteryl (2'-hydroxy)-3-ethyl ether reduce the energy content of the phase transition nearly as effective as cholesterol, cholesteryl n-propyl ether has only a small effect. Although cholesteryl acetate, and cholesteryl methoxymethyl ether have no condensing or permeability-reducing effect, they have a considerable effect on the gel-to-liquid-crystalline phase transition. Cholesteryi isopropyl ether and cholesteryl butyl ether have no effect. It is concluded that a free 30-hydroxy group is not a prerequisite to observe a sterol-like effect in membranes. However, the interfacial stability and the orientation of the sterol and oxygen moiety at the sterol 3-position are important.

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Section: Discussionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The effect of the sterol oxygen function on the interaction with phospholipids

Demel

Lala

Kumari

et al. 1984

Biochimica et Biophysica Acta (BBA) - Biomembranes

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“…Cholesterol is a membrane building block and as such it interacts strongly with most of the phospholipids present in biological membranes [1]. As a consequence of this interaction, the membrane physical properties are altered in such a way that the gel state is less ordered (spacing effect) and the liquid state more ordered (condensing effect).…”

Section: Introductionmentioning

confidence: 99%

“…As a consequence of this interaction, the membrane physical properties are altered in such a way that the gel state is less ordered (spacing effect) and the liquid state more ordered (condensing effect). Structural requirements, such as a 3/3-OH group, a flexible side-chain and a plane nucleus, are prerequisite for maximizing these effects [1]. In addition, cholesterol and derivatives affect also the lipid polymorphism of non-bilayer-forming lipids [2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Sterol-phospholipid interactions in model membranes Effect of polar group substitutions in the cholesterol side-chain at C20 and C22

Gallay

Kruijff

Demel

1984

Biochimica et Biophysica Acta (BBA) - Biomembranes

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The interactions of phospholipids with four different cholesterol derivatives substituted with one OH or one keto group at position C2o or C22 of the side-chain were studied. The derivatives were the 22,R-hydroxy; 22,S-hydroxy; 22-keto-and 20,S-hydroxycholesterol. Two aspects of the interactions were investigated: (1) the effect of the cholesterol derivatives on the gel--, liquid crystalline phase transition of dipalmitoylphosphatidylcholine (DPPC) and of dielaidoyiphosphatidylethanolamine (DEPE) monitored by differential scanning calorimetry and (2) The effect on the lamellar--, hexagonal H n phase transition of DEPE monitored by DSC and by 3t P-NMR to determine structural changes. The gel ---, liquid crystalline phase transition was affected by the cholesterol derivatives to a much larger extent in the case of DPPC than of DEPE. In both cases, there was a differential effect of the four derivatives, the 22,R-hydroxycholesterol being the less effective. In DPPC-sterol 1 : 1 systems, 22,R-hydroxycholesterol does not suppress the melting transition, the AH values becomes 7.1 kcal. mol-1 as compared to 8.2 kcal. mol-1 for the pure lipid. 22,S-OH cholesterol has a much stronger effect (AH = 3.1 kcai. tool-1) and 22-ketocholesterol suppresses the transition completely. In DEPE mixtures of all these compounds, the melting transition of the phospholipid is still observable. The transition temperature was shifted to lower values (-13.5°C in the presence of 20,S-OH cholesterol). The AH of the transition was lowered by these compounds except in DEPE-22,R-OH cholesterol mixtures and the cooperativity of the transition (reflected by the width at half peak height) was reduced. The lameilar --, hexagonal H t~ phase transition was also affected by the presence of these cholesterol derivatives. The transition temperature value was depressed with all these compounds. 20,S-OH cholesterol was the most effective followed by 22,R-OH cholesterol. The AH of the transition was not strongly affected. The molecular intedacial properties of these derivatives were studied by the monomolecular film technique. It is most likely that 22,R-OH cholesterol due to the hydroxyl groups at the * To whom correspondence should be sent at (present address): E.R. No. 64 du Centre National de la Recherche Scientifique, Unit~ d'Enseignements et de Recherche Biom~dicale des Saints-P~res, 45, rue des Saints-P~res, 75270 Paris C~dex 06, France. Abbreviations: DEPE, 1,2-dielaidoyl-sn-glycero-3-phosphoethanolamine; DOPE, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine; DPPC, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine; DOPC, 1,2-dioleoyl-sn-glycero-3-phosphocholine; EDTA, ethylenediaminetetraacetic acid; 22,R-OH cholesterol, (22,22,(22,20, 22-ketocholesterol, 5-cholestene-3fl-ol-22-one; cytochrome P-450sc¢, cytochrome P-450 specific for the side-chain cleavage of cholesterol.0005-2736/84/$03.00 © 1984 Elsevier Science Publishers B.V. 973~-and 22,R-positions orients with the sterol nucleus lying flat at the air/water interface, since the compression isotherm...

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Effect of low frequency, low amplitude magnetic fields on the permeability of cationic liposomes entrapping carbonic anhydrase: I. Evidence for charged lipid involvement

Ramundo-Orlando¹,

Morbiducci

Mossa³

et al. 2000

Bioelectromagnetics

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The influence of low frequency (4-16 Hz), low amplitude (25-75 mu T) magnetic fields on the diffusion processes in enzyme-loaded unilamellar liposomes as bioreactors was studied. Cationic liposomes containing dipalmitoylphosphatidylcholine, cholesterol, and charged lipid stearylamine (SA) at different molar ratios (6:3:1 or 5:3:2) were used. Previous kinetic experiments showed a very low self-diffusion rate of the substrate p-nitrophenyl acetate (p-NPA) across intact liposome bilayer. After 60 min of exposure to 7 Hz sinusoidal (50 mu T peak) and parallel static (50 mu T) magnetic fields the enzyme activity, as a function of increased diffusion rate of p-NPA, rose from 17 +/- 3% to 80 +/- 9% (P < .0005, n = 15) in the 5:3:2 liposomes. This effect was dependent on the SA concentration in the liposomes. Only the presence of combined sinusoidal (AC) and static (DC) magnetic fields affected the p-NPA diffusion rates. No enzyme leakage was observed. Such studies suggest a plausible link between the action of extremely low frequency magnetic field on charged lipids and a change of membrane permeability.

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The function of sterols in membranes

Cited by 1,272 publications

References 122 publications

The effect of the sterol oxygen function on the interaction with phospholipids

The effect of the sterol oxygen function on the interaction with phospholipids

Sterol-phospholipid interactions in model membranes Effect of polar group substitutions in the cholesterol side-chain at C20 and C22

Effect of low frequency, low amplitude magnetic fields on the permeability of cationic liposomes entrapping carbonic anhydrase: I. Evidence for charged lipid involvement

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