Effect of added α-lactalbumin protein on the phase behavior of AOT–brine–isooctane systems

Rohloff, Catherine M.; Shimek, Justin W.; Dungan, Stephanie R.

doi:10.1016/s0021-9797(03)00079-1

Cited by 13 publications

(26 citation statements)

References 49 publications

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“…At the most alkaline pH, where the protein was found primarily in the aqueous phase (Figure ), the correlation length of the droplets in the organic phase corresponded closely to the radius of AOT microemulsion droplets formed in the absence of α-LA (11 nm) . As the pH decreased, correlation lengths in the w/o microemulsion increased.…”

Section: Resultsmentioning

confidence: 74%

“…The water content of the oil-continuous microemulsion was measured by using a Mettler DL18 Karl Fischer titrator (Mettler-Toledo, Inc., Hightstown, NJ). Nuclear magnetic resonance spectroscopy was used to measure AOT and isooctane concentrations in the organic and aqueous phases . Small volumes (16−30 μL) of these solutions were dissolved in 0.8 mL of DMSO that contained 1−5 mg TMSP.…”

Section: Methodsmentioning

confidence: 99%

“…Previous research in single-phase organic , or aqueous − surfactant solutions, as well as in aqueous/organic mixtures, − provides evidence that proteins can shift the phase boundaries of such solutions. These effects of proteins on surfactant phase behavior are generally associated with intimate interactioneither peripheral or intrinsicbetween the protein molecule and surfactant, often accompanied by changes in nanostructure morphology.…”

Section: Introductionmentioning

confidence: 99%

“…α-LA assumes this state through removal of bound calcium and low salt, at acid pH, or with partial or complete disulfide bond reduction . Interaction with negatively charged surfactant interfaces also may induce the molten globule state for this protein, as indicated by results with phospholipid bilayers, − SDS, or AOT …”

Section: Introductionmentioning

confidence: 99%

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Effect of α-Lactalbumin on the Phase Behavior of AOT−Brine−Isooctane Mixtures: Role of Charge Interactions

et al. 2005

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We have found that both electrostatic and hydrophobic interactions are involved in the ability of the protein alpha-lactalbumin (alpha-LA) to affect the self-assembly of the anionic surfactant sodium bis(ethylhexyl) sulfosuccinate (AOT, 3.5 wt %) in equivolume mixtures of organic and aqueous solutions. The composition and size of AOT phase structures that form in the presence of 0.35 wt % protein were evaluated as a function of pH and ionic strength. In the absence of protein, AOT forms water-in-oil microemulsion droplets for all pH and salt concentrations studied here. The presence of the protein in the water-in-oil microemulsion phase boosts water solubilization and droplet size, as the spontaneous curvature of the surfactant interface becomes less negative. Aggregates of protein, surfactant, and oil also form in the water-continuous phase. The size and composition of structures in both phases can be tuned in the presence of protein by varying the pH and ionic strength. alpha-LA induces the appearance of an anisotropic surfactant phase at pH <5.8. At intermediate salt concentrations, a third isotropic, viscous aqueous phase appears that contains 55-60% of the protein, 10-14% of the surfactant, and significant amounts of oil. Circular dichroism and fluorescence spectroscopy indicate that the protein contains enhanced alpha-helical secondary structure when self-assembling with surfactant, and has a loosened tertiary structure. The protein does not interact with the surfactant as an unfolded random coil. Although the conformation of alpha-LA in aqueous salt solutions is known to depend on pH, when self-assembling with AOT the protein adopts a structure whose features are quite pH insensitive, and likely reflect an intrinsic interaction with the interface.

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Section: Resultsmentioning

confidence: 74%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of α-Lactalbumin on the Phase Behavior of AOT−Brine−Isooctane Mixtures: Role of Charge Interactions

et al. 2005

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“…47) The separation of xylose reductase 48) and lysozyme from egg white 49) have been reported using microemulsion technology, and the ability of reversed micellar systems to act as a bioseparation technique for isolation and puriˆcation of proteins has been reviewed by Pires, et al 50) Promising application of the ability of microemulsions to separate and concentrate proteins may be in the separation and puriˆcation of heterogeneous proteins, such as caseins and whey proteins, resulting in large-scale production of individual proteins with increased value. Recently, the incorporation of immunoglobulin G 43) and a-lactalbumin 51) into microemulsion systems formulated with AOT, a non-foodgrade anionic surfactant and isooctane has been reported.…”

Section: Oil Suspensionsmentioning

confidence: 99%

Lipid Carriers: A Versatile Delivery Vehicle for Proteins and Peptides

2008

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Lipid based carriers have attracted increasing scientiˆc and commercial attention during the last few years as an alternative material for the delivery of peptides and proteins concerned with stability issues. This article presents an overview of diŠerent types of biocompatible and versatile lipid-based carriers employed for the delivery of therapeutic proteins and peptides. Such delivery systems are discussed and exempliˆed regarding both more traditional lipid based delivery systems such as liposomes and lipid emulsions as well as more novel structures, e.g., lipid microtubules, microbubbles, and solid lipid nanoparticles.

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