Can affinity interactions influence the partitioning of glucose-6-phosphate dehydrogenase in two-phase aqueous micellar systems?

Abstract

Recebido em 8/2/07; aceito em 27/11/07; publicado na web em 8/7/08In this work, we provide an investigation of the role and strength of affinity interactions on the partitioning of the glucose-6-phosphate dehydrogenase in aqueous two-phase micellar systems. These systems are constituted of micellar surfactant solutions and offer both hydrophobic and hydrophilic environments, providing selectivity to biomolecules. We studied G6PD partitioning in systems composed of the nonionic surfactants, separately, in the presence and absence of affinity ligands. We observed that G6PD partitions to the micelle-poor phase, owing to the strength of excluded-volume interactions in these systems that drive the protein to the micellepoor phase, where there is more free volume available.

Liquid–liquid extraction of biomolecules: an overview and update of the main techniques

“…64,65 In these systems, an aqueous surfactant solution, under appropriate conditions, spontaneously separates into two predominantly aqueous, yet immiscible, liquid phases, one of which has a greater concentration of micelles than the other. 66 In recent times ATPMS have been investigated for possible industrial applications.…”

“…Cloud point can be increased by addition of long-chain nonpolar compounds, anions that are water structure breakers (large, polarizable anions, soft bases, SCN − , I − ), and certain cations (polyvalent cations, H + , Li + ) owing to their salting-in effect in water. 65,96,97 The presence of salts in two-phase aqueous systems can influence protein partition. The addition of salts, even at milimolar concentrations, can influence the electrically loaded molecule partition.…”

“…Accordingly, a fundamental understanding of how salts affect the behavior of aqueous surfactant solutions may lead to a more effective utilization of these systems in various practical applications, for example protein purification. 65 Another option to optimize the biomolecules purification in ATPMS is the use of affinity interactions. 69,76,100 A particularly attractive feature of these systems is the prospect of being able to select a target protein by preferentially extracting it into the micelle-rich phase, while simultaneously removing most of the impurities into the micellepoor phase, owing to the excluded-volume interactions between these impurities and the micelles.…”

“…Nevertheless, there have been relatively few attempts to apply the concept of free affinity ligands to carry out bioseparations in ATPMS. 63,65,101 The triazine dyes Cibacron Blue 3GA and Procion Red HE-3B have been studied as affinity ligands for G6PD purification using chromatography. 102,103 Lopes et al 65 present a discussion, based on experimental results, about the role of affinity interactions on the partitioning of the hydrophilic enzyme G6PD in ATPMS composed of the surfactants Triton X-114 and C 10 E 4 .…”

“…63,65,101 The triazine dyes Cibacron Blue 3GA and Procion Red HE-3B have been studied as affinity ligands for G6PD purification using chromatography. 102,103 Lopes et al 65 present a discussion, based on experimental results, about the role of affinity interactions on the partitioning of the hydrophilic enzyme G6PD in ATPMS composed of the surfactants Triton X-114 and C 10 E 4 . According to the results, in spite of the clear presence of affinity interactions, these were not strong enough to significantly overcome the excluded-volume effect and drive the enzyme preferentially to the micelle-rich phase containing the affinity ligands.…”