Water-Mediated Effects of PEG on Membrane Properties and Fusion

Arnold, Klaus; Herrmann, Andreas; Gawrisch, Klaus; Pratsch, Lothar

doi:10.1007/978-1-4613-1659-6_19

Cited by 28 publications

(26 citation statements)

References 48 publications

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“…Most of these recognize the dehydrating ability of PEG, but stress different structural consequences of this property. The importance of nonbilayer structures has been stressed by Boni et al (1 98 1 b; 1984a,b), although Tilcock and Fisher (1982) and Arnold et al (1983), also using 31P N M R techniques, found no evidence for nonbilayer structures induced by PEG. Arnold et al (1983) suggested that impurities in the PEG used by Boni et al could have explained their detection of nonbilayer structures.…”

Section: Effect Of Dextran On the Fusion Of Dppc Revmentioning

confidence: 98%

“…The importance of nonbilayer structures has been stressed by Boni et al (1 98 1 b; 1984a,b), although Tilcock and Fisher (1982) and Arnold et al (1983), also using 31P N M R techniques, found no evidence for nonbilayer structures induced by PEG. Arnold et al (1983) suggested that impurities in the PEG used by Boni et al could have explained their detection of nonbilayer structures. From electron microscopy and turbidity measurements, S5ez et al (1982) have suggested that PEG locally solubilized the membrane bilayer, causing fusion by a process of rupture and resealing of the membrane.…”

Section: Effect Of Dextran On the Fusion Of Dppc Revmentioning

confidence: 98%

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Rate and extent of polyethylene glycol-induced large vesicle fusion monitored by bilayer and internal contents mixing

Parente¹,

Lentz²

1986

Biochemistry

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Poly(ethylene glycol) (PEG) of average molecular weight 8000 was used to mediate the fusion of large unilamellar vesicles composed of dipalmitoylphosphatidylcholine. Fusion was monitored by fluorescence assays of lipid mixing and aqueous contents mixing. The extent of lipid mixing, as monitored by DPHpPC fluorescence lifetime, indicated that large unilamellar vesicles underwent a single fusion cycle when incubated with PEG and subsequently diluted into buffer. The ANTS/DPX assays for contents mixing and leakage indicated that, while addition and dilution of PEG were accompanied by extensive contents leakage, this occurred on a much different time scale as compared to contents mixing. Both the lipid-mixing and contents-mixing assays gave comparable estimates for the number of rounds of fusion that occurred in a given time following PEG addition, although the contents-mixing assay always yielded an estimate 10-15% larger than the lipid-mixing assay. These assays were used to evaluate several factors purported to influence PEG-induced fusion. First, the initial rate of fusion was found to be dependent on PEG concentration in the range of 0-35 wt %, while the extent of fusion was not. In addition, a substantial rate enhancement occurred when vesicles were incubated with greater than 26% PEG. Second, the creation of an osmotic gradient upon dilution of vesicle-PEG mixtures was shown to have no effect on either the extent or the initial rate of fusion. Consistent with this observation, both contents and lipid mixing were found to occur prior to and independent of the dilution of the PEG-vesicle suspension. Third, impurities, either present in our commercially available PEG or added to vesicle-PEG mixtures, also had no effect on the rate or extent of fusion. Fourth, another dehydrating polymer, dextran (average mol wt 9000), was capable of promoting fusion, though at a much lower rate than PEG. These results suggest that even partial bilayer dehydration accompanied by vesicle collapse and close interbilayer contact may be sufficient to induce vesicle fusion.

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Section: Effect Of Dextran On the Fusion Of Dppc Revmentioning

confidence: 98%

Section: Effect Of Dextran On the Fusion Of Dppc Revmentioning

confidence: 98%

Rate and extent of polyethylene glycol-induced large vesicle fusion monitored by bilayer and internal contents mixing

Parente¹,

Lentz²

1986

Biochemistry

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“…The volume fraction in the bulk, φ 0 = υc, is determined by the partial specific volume, υ, and the polymer concentration, c, in g/cm 3 . The volume of one molecule is defined as ν = υM/N A , where M and N A are the molar mass and the Avogadro number.…”

Section: Static Thickness and Profilementioning

confidence: 99%

“…That is a surprise, as the surface charge [2] and the dielectric permittivity in the bulk of the solution [3] practically do not change, and at neutral polymer absorption, ζ decreases because of a shift of shear plane [4]. The theory developed by Brooks [5] explains this effect with a change of the potential profile, due to extrusion of counterions by adsorbed polymer.…”

Section: Introductionmentioning

confidence: 97%

Dependence of depletion layer thickness on polymer concentration determined by Vincent's pragmatic and Donath's electrophoretic theories

Zhivkov

2007

Journal of Colloid and Interface Science

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“…One of the primary effects by which fusion is induced is thought to be the reduction of water activity by PEG, leading to an effective membrane dehydration (Arnold et al, 1983;MacDonald, 1985). A possible mechanism by which this may take place is the modulation of the lipid phase behavior resulting from the reduction in lipid hydration.…”

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confidence: 99%

Polymorphic phase behavior of lysopalmitoylphosphatidylcholine in poly(ethylene glycol)-water mixtures

King¹,

Marsh²

1989

Biochemistry

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ABSTRACT:The polymorphic phase behavior of l-palmitoyl-2-lyso-sn-glycero-3-phosphocholine dispersions in excess water has been studied as a function of temperature and poly(ethy1ene glycol) (PEG) concentration, using proton dipolar-decoupled 31P N M R spectroscopy and turbidity measurements. The phase behavior was found to depend on both lipid concentration and PEG concentration, and most of the N M R experiments were conducted at a lipid concentration of 15 mg/mL. At low PEG concentrations (0-12 wt %), a thermotropic transition occurs at 3-5 "C with increasing temperature, from an interdigitated lamellar gel (LBi) phase to a normal micellar phase. At intermediate PEG concentrations (12-20 wt %), thermotropic transitions take place with increasing temperature, first from the lamellar gel phase to a fluid cubic (Q,) phase and then at higher temperatures from the cubic phase to the micellar phase. At intermediate PEG concentrations above the former range (20-30 wt %), thermotropic transitions take place with increasing temperature, first from the lamellar gel phase to the cubic phase, then from the cubic phase to a normal hexagonal (HI) phase, and finally from the hexagonal phase to the micellar phase. At high PEG concentrations (>30 wt %), a thermotropic transition takes place with increasing temperature from the lamellar gel phase directly to the fluid hexagonal phase. At these high PEG concentrations, the micellar phase is not attained within the accessible temperature range (190 "C). The kinetics of some of the phase changes are slow with half-times of the order of 15 min, and considerable hysteresis, with coexisting phases, is observed on the downward temperature scans. The turbidity measurements indicate considerable changes in optical density in single phase regions, presumably corresponding to changes in aggregate size. Discontinuities in the temperature dependence of the optical density are observed corresponding to some of the phase boundaries, and conversion to the micellar phase is evidenced by the transition to optical clarity.

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Water-Mediated Effects of PEG on Membrane Properties and Fusion

Cited by 28 publications

References 48 publications

Rate and extent of polyethylene glycol-induced large vesicle fusion monitored by bilayer and internal contents mixing

Rate and extent of polyethylene glycol-induced large vesicle fusion monitored by bilayer and internal contents mixing

Dependence of depletion layer thickness on polymer concentration determined by Vincent's pragmatic and Donath's electrophoretic theories

Polymorphic phase behavior of lysopalmitoylphosphatidylcholine in poly(ethylene glycol)-water mixtures

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