Effect of Water Polarized at the Carbonyl Groups of Phosphatidylcholines on the Dipole Potential of Lipid Bilayers

Díaz, Sergio; Amalfa, F.; Lopez, Augustin; Disalvo, E.A.

doi:10.1021/la981235f

Cited by 55 publications

(52 citation statements)

References 22 publications

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“…The obvious interpretation of this is that the sugar molecules increase the area through intercalation between the lipid head groups. Other experimental approaches have reached analogous conclusions in work on lipid bilayers (19,20,24,32), and Viera et al (33) found that trehalose that was bound to a bilayer during dehydration remained associated for hours upon rehydration in buffer without sugar. Most recently, the interaction hypothesis has been supported by many molecular dynamics simulations (see, e.g., refs.…”

mentioning

confidence: 75%

Reconciliation of opposing views on membrane–sugar interactions

Andersen

Wang

Arleth

et al. 2011

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

140

177

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It is well established that small sugars exert different types of stabilization of biomembranes both in vivo and in vitro. However, the essential question of whether sugars are bound to or expelled from membrane surfaces, i.e., the sign and size of the free energy of the interaction, remains unresolved, and this prevents a molecular understanding of the stabilizing mechanism. We have used smallangle neutron scattering and thermodynamic measurements to show that sugars may be either bound or expelled depending on the concentration of sugar. At low concentration, small sugars bind quite strongly to a lipid bilayer, and the accumulation of sugar at the interface makes the membrane thinner and laterally expanded. Above ∼0.2 M the sugars gradually become expelled from the membrane surface, and this repulsive mode of interaction counteracts membrane thinning. The dual nature of sugar-membrane interactions offers a reconciliation of conflicting views in earlier reports on sugar-induced modulations of membrane properties.membrane interface | membrane structure | preferential binding | preferential exclusion | interaction free energy S mall sugars such as the disaccharides sucrose and trehalose are among the so-called osmolytes (1) or compensatory solutes (2), which are accumulated in response to environmental stress in virtually all taxa. Their function is to act as inert regulators of the osmotic pressure, but they also optimize the physical properties of the cytosol (3) and stabilize biomolecular conformations against cold, drought, and heat (4-7). The same small carbohydrates have also proven useful in vitro as protectants or excipients for biopreservation (8). Many reports have shown that membranous structures are particularly stabilized by small sugars (4, 6, 9), but the definition of stabilization covers a wide range of biological and physical parameters. Thus, studies on intact cells have documented improved survival following exposure to heat, cold, drought, or chemical stressors (6,10,11). Other works have analyzed stabilization on the basis of phenomenological properties of model membranes, for example, the leakage or intermixing of probes in liposomes (12, 13). Finally, stability has been discussed with respect to rigorous physical parameters such as the structure or mechanical properties of lipid bilayers (14, 15). The current work addresses membrane dimensions and the thermodynamics of interaction with the purpose of elucidating fundamental aspects of membrane-sugar interrelationships. The different observations of sugar stabilization have sparked a large number of studies on sugars and model membranes (usually phospholipid bilayers) over the past 30 y. Investigations of fully hydrated membranes show an interesting tendency to fall into two groups with mutually conflicting conclusions. Thus, many investigations have suggested direct (favorable) interaction of sugars and the phospholipid interface (16-23), and it is obvious that such interactions could be the origin of sugar effects, for example, through int...

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mentioning

confidence: 75%

Reconciliation of opposing views on membrane–sugar interactions

Andersen

Wang

Arleth

et al. 2011

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

140

177

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“…DMPC/ DDMDDAC systems studied contained: 0.1%, 0.5%, 1% and 5% of DDMDDAC. All samples were prepared by 10 cycles of successive sonication at 303 K (30 min) and cooling at 278 K. D 2 O was used as a solvent in preparation of the DMPC/surfactant mixture for better visualization of the carbonyl region in the FTIR spectroscopy [20]. Sonication at a temperature higher than the phase transition point prevents phase separation [21] and allows better incorporation of the surfactant molecules into phospholipids bilayers [22].…”

Section: Sample Preparationmentioning

confidence: 99%

Structural and spectroscopic studies of DMPC/cationic surfactant system

Kozak

Wypych

Szpotkowski

et al. 2010

Journal of Non-Crystalline Solids

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“…Substitution of these water molecules by hydrogen-bonding compounds, such as trehalose at a 0.15 M concentration, results in a decrease of the dipole potential of DMPC in the gel state of about 80 mV. 6,7 However, when carbonyls of the ester region are replaced by ether-linked lipids or trehalose is present in the aqueous solution, the remaining value of the monolayer potential is still significant. This suggests that, in addition to carbonyls and their hydration water, other structural groups at the lipid/water interface may be contributing to the dipole potential.…”

Section: Introductionmentioning

confidence: 99%

Contribution of Phosphate Groups to the Dipole Potential of Dimyristoylphosphatidylcholine Membranes

et al. 2001

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Phloretin, a molecule which is known to decrease the dipole potential of lipid membranes, has a little effect on the CdO frequencies of dimyristoylphosphatidylcholine bilayers (DMPC) in comparison to that observed on the phosphates. In the first case, the frequency is displaced very slightly to higher values, while a pronounced downward shift is observed on the asymmetric vibration frequencies of the phosphates. The effect of phloretin on the phosphate groups is correlated with a decrease in the monolayer potential of DMPC in the gel and in the liquid crystalline state. From the comparison with monolayers spread on water and on 0.15 M trehalose, it is concluded that the PdO bonds of the phosphates can contribute to the dipole potential of the membrane in addition to the contribution given by the orientation of the -P-N + dipole.

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Effect of Water Polarized at the Carbonyl Groups of Phosphatidylcholines on the Dipole Potential of Lipid Bilayers

Cited by 55 publications

References 22 publications

Reconciliation of opposing views on membrane–sugar interactions

Reconciliation of opposing views on membrane–sugar interactions

Structural and spectroscopic studies of DMPC/cationic surfactant system

Contribution of Phosphate Groups to the Dipole Potential of Dimyristoylphosphatidylcholine Membranes

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