Theoretical Aspects of Partitioning

Brooks, Donald E.; Sharp, Kim A.; Fisher, Derek

doi:10.1016/b978-0-12-733860-6.50009-8

Cited by 65 publications

(39 citation statements)

References 92 publications

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“…When a mixture of proteins is added to an aqueous two-phase system, each type of protein partitions uniquely between the phases. The partitioning behavior of a protein in a given twophase system is governed predominantly by its size, surface chemistry and net charge, with other, usually smaller, contributions made by forces associated with the dipole moment and polarizability of the protein (Johansson, 1974b;Brooks et al, 1985;Haynes et al, 1989b). As shown by Hustedt et al (1990), subtle changes in any of these properties can lead to noticeable changes in partitioning behavior.…”

Section: Spainmentioning

confidence: 96%

“…For realistic engineering applications, it is essential that electrostatic forces be included in any model for aqueous solutions containing proteins. To model protein partition coefficients in systems containing electrolytes, Brooks (Walter et al, 1985) and King et al (1988) extended their theories to include the effect of the interfacial-electrostaticearly model was provided by Brooks et al (1985), who used the Flory-Huggins theory to correlate phase-diagram and protein partition-coefficient data. Among others, Walter et al (1991) have questioned the applicability of the Flory-Huggins theory, which assumes that all polymer segments are uniformly potential difference.…”

Section: Spainmentioning

confidence: 99%

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Application of integral‐equation theory to aqueous two‐phase partitioning systems

et al. 1993

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Section: Spainmentioning

confidence: 96%

Section: Spainmentioning

confidence: 99%

Application of integral‐equation theory to aqueous two‐phase partitioning systems

et al. 1993

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“…The curve separates the two-phase region, located above the binodal, from the one phase region, below the binodal, and was determined at 4 and 208C. A decrease in temperature can be used to inhibit phase separation of PEG/salt-based ATPS if their composition is close to the binodal curve (Albertsson, 1986;Brooks et al, 1985). However, the ILbased ATPS showed the opposing behavior.…”

Section: Characterization Of Il-based Atpsmentioning

confidence: 99%

Ionic liquids for aqueous two‐phase extraction and stabilization of enzymes

Dreyer

Kragl

2007

Biotech & Bioengineering

205

134

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The ionic liquid (IL) Ammoeng110 contains cations with oligoethyleneglycol units and was found to be highly effective for the formation of aqueous two-phase systems (ATPS) that can be used for the biocompatible purification of active enzymes. Above critical concentrations of the IL and an inorganic salt in aqueous solution, phase separation takes place resulting in the formation of an IL-enriched upper and a salt-enriched lower phase. For the optimization of the composition of IL-based ATPS with regard to the extraction of catalytically active enzymes, the Box-Wilson method of experimental design was successfully applied; IL-based ATPS proved to be suitable for the purification and stabilization of two different alcohol dehydrogenases (from Lactobacillus brevis and a thermophilic bacterium). Both enzymes were enriched in the IL-containing upper phase resulting in an increase of specific activity by a factor of 2 and 4 respectively. Furthermore, the presence of IL within the system provided the opportunity to combine the extraction process with the performance of enzyme-catalyzed reactions. The IL was found to exhibit a stability improving effect on both enzymes and a solubility enhancing effect on hydrophobic substrates. Thus the conversion and volumetric productivity of ADH catalyzed reduction of acetophenone could be increased significantly.

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“…Protein partition coefficients are influenced by a number of factors and can be manipulated in a number of ways": (1) protein size-the partition coefficient decreases when the protein molecular weight increases; (2) polymer molecular weight -decreasing the molecular weight of one polymer, say polymer A, while fixing the total polymer concentration on a weight/weight basis increases the affinity of the protein for the phase rich in polymer A'; (3) polymer concentration-increasing the polymer concentration gives rise to more extreme partitioning of proteins; (4) hydrophobic/hydrophillic nature of the protein and polymer surfaces-these properties are more important at the isoelectric point pH than away from it; (5) protein surface charge, salt concentration, salt type, pH and ionic strength; (6) temperature; (7) affinity ligands. Although some exceptions are known [particularly for trends (1) and (2)], these trends are widely accepted as general behavior of proteins in aqueous two-phase systems.…”

Section: Introductionmentioning

confidence: 99%

Protein partitioning at the isoelectric point: Influence of polymer molecular weight and concentration and protein size

Forciniti

Hall

Kula

1991

Biotech & Bioengineering

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We report the partition coefficient, K(p') at the isoelectric point of lysozyme, chymotrypsinogen A, albumin, transferrin, and catalase in 64 different polyethylene(PEG)/ dextran(Dx)/water systems. We study the trends of the partition coefficient with protein type, polymer concentration, and polymer molecular weight. We find that the partition coefficient decreases with increasing tie line length for lysozyme, albumin, transferrin, and catalase for which K(p) is less than 1, but increases for chymotrysinogen for which K(p) is larger than 1. The effect of the tie line length on the partition coefficient is larger for the large proteins than for the small proteins. The partition coefficient decreases with increasing protein molecular weight except for lysozyme suggesting that lysozyme is present as a dimer or a trimer. The partition coefficient decreases with increasing PEG molecular weight, but the magnitude of the increase is larger for the smaller PEG molecular eights and tends to level of at high PEG molecular weight. The partition coefficient increases with increasing dextran (Dx) molecular weight for chymotrypsinogen but decreases for catalase. The partition coefficients of lysozyme, albumin, and transferrin increase with increasing Dx molecular weight from Dx 10(4) to Dx 1.1 x 10(5) and then slightly decrease from Dx 1.1 x 10(5) to Dx 5 x 10(5). The experimental results are analyzed using a statistical thermodynamics model. The experimental results are analyzed using a statistical thermodynamics model. The experiments suggest that protein partitioning at the isoelectric point in aqueous two-phase systems is strongly related to the size of the proteins and polymers. Finally, the impossibility of obtaining data completely independent of polymer concentration is emphasized.

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Theoretical Aspects of Partitioning

Cited by 65 publications

References 92 publications

Application of integral‐equation theory to aqueous two‐phase partitioning systems

Application of integral‐equation theory to aqueous two‐phase partitioning systems

Ionic liquids for aqueous two‐phase extraction and stabilization of enzymes

Protein partitioning at the isoelectric point: Influence of polymer molecular weight and concentration and protein size

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