Small‐Angle Neutron Scattering Studies of Protein‐Reversed Micelle Complexes

Sheu, Eric Y.; Göklen, Kent E.; Hatton, T. Alan; Chen, S.-H.

doi:10.1002/btpr.5420020405

Cited by 61 publications

(20 citation statements)

References 26 publications

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“…As for both trioctylmethylammonium chloride and AOT a similar intercept is found, one would expect that the size of the reversed micelles is comparable. This is however unlikely, as AOT micelles have, under the experimental conditions used, a M', of about 15 [42], whereas trioctylmethylammonium chloride reversed micelles have a w, of 6 under the experimental conditions used. For trioctylmethylammonium chloride micelles a smaller radius is expected but no data are available.…”

Section: Resultsmentioning

confidence: 95%

“…Above, we interpreted the intercept as the maximal M , that can be incorporated into reversed micelles without an increase in micellar size. Sheu et al [42] demonstrated that the radii of filled and empty reversed AOT micelles, prepared by extraction of cytochrome c from a 0.1 M KCl solution are 4.57 nm and 4.61 nm, respectively. As for both trioctylmethylammonium chloride and AOT a similar intercept is found, one would expect that the size of the reversed micelles is comparable.…”

Section: Resultsmentioning

confidence: 99%

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Protein transfer from an aqueous phase into reversed micelles

Wolbert¹,

Hilhorst²,

Voskuilen³

et al. 1989

European Journal of Biochemistry

113

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Proteins are spontaneously transferred from an aqueous solution into reversed micelles, provided the aqueous phase has the proper composition. Besides the composition of the aqueous phase, the composition of the organic phase and the properties of the proteins also play a role. We studied uptake profiles of 19 proteins as a function of pH of the aqueous solution. The organic phase consisted of trioctylmethylammonium chloride and nonylphenol pentaethoxylate (Rewopal HV5) as surfactant, octanol as cosurfactant and isooctane as continuous phase. In all cases, except for rubredoxin, proteins were transferred at pH values above their isoelectric point. The pH where maximal solubilization takes place can be described by the relationship: pHoptimum = isoelectric point f0.11 x 1O-j M , -0.97. So, the larger the protein, the more charge is needed to provide the energy required for the adaptation of the micellar size to the protein size. For protein transfer into sodium di-(2-ethylhexyl)sulphosuccinate Several fields of application for reversed micelles in biotechnology have been suggested (for reviews see [l -41). One of the potential applications is the extraction of proteins from an aqueous or solid phase via a reversed micellar phase into a second aqueous phase. This double transfer process is based on the ability of reversed micelles to extract proteins from an aqueous solution into their aqueous core. Most proteins retain their native conformation during the transfer process and remain in an active form when incorporated into reversed micelles [ 1 -61.Hatton and coworkers have shown that this technique is feasible for the extraction of proteins from a fermentation broth [7] and Leser et al. [8] demonstrated its applicability for the extraction of proteins from the solid phase. Previously [9] we reported that a-amylase could be extracted from an aqueous solution into a reversed micellar medium and re-extracted into a second aqueous phase in a continuous process with a yield of 45% and a concentration factor of eight with respect to enzyme activity. Addition of the nonionic surfactant nonylphenol pentaethoxylate (Rewopal HV5) to the organic phase, led to an increase both in the degree of solubilization of the enzyme and in the pH range in which solubilization occurs [lo]. By increasing the rate of mass transfer and the distribution coefficient of the enzyme during forward extraction, the yield has been improved to 85% and the concentration factor to 17 [ll].From the results published to date, it becomes evident that protein partitioning depends on the pH, ionic strength and type of ions present in the aqueous phase, on the type of surfactant, cosurfactant and organic solvent used, on micellar size, on the temperature and on properties of the protein [ 5 , 12 -161. However, no information is available on the mechanisms by which these variables affect protein partitioning. In this study the partitioning behaviour is related to such protein properties as size, isoelectric point and distribution of charged groups over th...

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Protein transfer from an aqueous phase into reversed micelles

Wolbert¹,

Hilhorst²,

Voskuilen³

et al. 1989

European Journal of Biochemistry

113

View full text Add to dashboard Cite

show abstract

“…Models proposed in the literature for reverse micelles characterization range from simple geometric models (22)(23)(24)(25)(26) to more rigorous molecular thermodynamic models (27)(28)(29). Several experimental methods and empirical models have been employed to determine the size and shape of reverse micellar aggregates.…”

Section: Introductionmentioning

confidence: 99%

Reverse Micellar Extraction of Bromelain from Pineapple (Ananas comosusL. Merryl) Waste: Scale-up, Reverse Micelles Characterization and Mass Transfer Studies

Hebbar

Hemavathi

Sumana

et al. 2011

Separation Science and Technology

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Scale-up studies for phase transfer mode of reverse micellar extraction are attempted for the separation and primary purification of bromelain (EC 3.4.22.33) from pineapple (Ananas comosus L. Merryl) waste. Characterization of reverse micelles and mass transfer studies for the real system has been attempted for the first time. Scale-up of the extraction process employing commercial grade surfactant cetyltrimethylammonium bromide (CTAB) and solvent isooctane resulted in purification of 2.43 fold with an activity recovery 81.3%. The reverse micellar size estimated using empirical and geometrical models indicated that the reverse micelles are large enough (R m ¼ 7.2-9.6 nm) to host bromelain molecules that are relatively smaller in size ($1.67 nm). The studies on the kinetics of mass transfer indicated a relatively slower rate (by $34%) of mass transfer in case of back extraction compared to forward extraction. Process scale-up did not significantly affect the extraction efficiency whereas purity of phase components played a major role. The mass transfer across the phases was high in the initial period of mixing for both forward and back extractions.

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“…ls718 The knowledge of the geometrical parameters of the microemulsion particles and their size distribution is very important to correctly interpret the observed phenomena and to develop good theoretical models of the driving forces responsible for both droplet formation and polymer and biopolymer solubilization in micro emulsion^.^-^^ In the last years these problems were often discussed and a number of experimental studies and theoretical models have been presented. [12][13][14][15][16][17][18][19] However, no unambiguous solution to these problems has been found, and the situation still remains controversial. It is the aim of this study to show that we can use dynamic (DLS) and static (SLS) light scattering experiments close to the so-called optical match point as a very sensitive method20 to quantitatively test the currently existing theories for the formation of microemulsion droplets on the one hand and for the protein solubilization in microemulsions on the other hand.…”

Section: Introductionmentioning

confidence: 99%

Optical Contrast Variation Experiments in Water-in-Oil Microemulsions: Size Distribution and Structure of Protein-Free and Protein-Containing Microemulsions

Christ¹,

Schurtenberger²

1994

J. Phys. Chem.

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We report on a study of protein-free and protein-containing AOT water-in-oil microemulsions with isooctane and decane as solvents by using static and dynamic light scattering measurements. In a first step, using a model of polydisperse layered spheres, we show that we can determine the size polydispersity y of the microemulsion droplets with very high precision because the variation of both the scattering intensity as well as the hydrodynamic radius with the water content are very sensitive to y in the vicinity of the optical match point of the microemulsion particles. In a second step, we then focus on the size and structural perturbations induced in the reverse micellar system upon solubilization of the enzyme a-chymotrypsin by using optical contrast variation techniques. In particular, we show that light scattering experiments close to the optical match point can be used as a very sensitive method in order to quantitatively test the currently existing theoretical models for protein solubilization in microemulsions.

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Small‐Angle Neutron Scattering Studies of Protein‐Reversed Micelle Complexes

Cited by 61 publications

References 26 publications

Protein transfer from an aqueous phase into reversed micelles

Protein transfer from an aqueous phase into reversed micelles

Reverse Micellar Extraction of Bromelain from Pineapple (Ananas comosusL. Merryl) Waste: Scale-up, Reverse Micelles Characterization and Mass Transfer Studies

Optical Contrast Variation Experiments in Water-in-Oil Microemulsions: Size Distribution and Structure of Protein-Free and Protein-Containing Microemulsions

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