Comparison of the Effects of Surface Tension and Osmotic Pressure on the Interfacial Hydration of a Fluid Phospholipid Bilayer

Söderlund, Tim; Alakoskela, Juha-Matti; Pakkanen, A; Kinnunen, Paavo K.J.

doi:10.1016/s0006-3495(03)74657-8

Cited by 70 publications

(54 citation statements)

References 57 publications

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“…Other stabilizing consequences of sugar binding have been put forward, and in this paper, we collectively refer to this interpretation as the "interaction hypothesis." In contrast to this, other works have concluded that the sugars are preferentially expelled from the hydration zone and that their effect on the membrane is exerted indirectly by the local osmotic imbalance and the concomitant increase in interfacial free energy (25)(26)(27)(28)(29)(30). We call this the "exclusion hypothesis.…”

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confidence: 81%

“…This ubiquitous correlation is explained by a preferential expulsion or exclusion that increases the interfacial free energy and thus promotes the stability of lipid phases with low water accessible areas. The exclusion hypothesis has been supported by some spectroscopic evidence (28), and recently both small-angle scattering studies (36,38) and vapor pressure measurements (39) have provided direct evidence for a partial depletion of sugar in the hydration zone of lipid bilayers. Several aspects of the exclusion hypothesis were recently discussed by Lenné et al (40) who concluded that "sugars partition away from the phospholipid headgroups, rather than inserting between the headgroups.…”

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confidence: 84%

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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: 81%

mentioning

confidence: 84%

Reconciliation of opposing views on membrane–sugar interactions

Andersen

Wang

Arleth

et al. 2011

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

140

177

View full text Add to dashboard Cite

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“…A higher osmolarity of the extravesicular environment yields vesicles with a higher membrane order and thus a higher degree of lipid packing. 36 …”

Section: Resultsmentioning

confidence: 99%

Electroformation of Giant Unilamellar Vesicles on Stainless Steel Electrodes

et al. 2017

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Giant unilamellar vesicles (GUVs) are well-established model systems for studying membrane structure and dynamics. Electroformation, also referred to as electroswelling, is one of the most prevalent methods for producing GUVs, as it enables modulation of the lipid hydration process to form relatively monodisperse, defect-free vesicles. Currently, however, it is expensive and time-consuming compared with other methods. In this study, we demonstrate that 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine GUVs can be prepared readily at a fraction of the cost on stainless steel electrodes, such as commercially available syringe needles, without any evidence of lipid oxidation or hydrolysis.

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“…Some researchers have focused on the difference of how kosmotropic and chaotropic solutes interact with lipid membranes [122][123][124]. Kosmotropes deplete the solution at the interface and increase the interfacial tension whereas chaotropes accumulate in the interface and decrease surface tension [125]. The changes in the structure of water due to these types of chemicals can be attributed to alterations in the hydrogen bonding network of water [126,127].…”

Section: Chemical Inhibition Of the Interdigitated Gel Phasementioning

confidence: 99%