Influence of salts on the coexistence curve and protein partitioning in nonionic aqueous two-phase micellar systems

Abstract

-Aqueous two-phase micellar systems (ATPMS) can be exploited in separation science for the extraction/purification of desired biomolecules. Prior to phase separation the surfactant solution reaches a cloud point temperature, which is influenced by the presence of electrolytes. In this work, we provide an investigation on the cloud point behavior of the nonionic surfactant C 10 E 4 in the presence of NaCl, Li 2 SO 4 and KI. We also investigated the salts' influence on a model protein partitioning. NaCl and Li 2 SO 4 promoted a depression of the cloud point. The order of salts and the concentration that decreased the cloud point was: Li 2 SO 4 0.5 M > NaCl 0.5 M ≈ Li 2 SO 4 0.2 M. On the other hand, 0.5 M KI dislocated the curve to higher cloud point values. For our model protein, glucose-6-phosphate dehydrogenase (G6PD), partitioning experiments with 0.5 M NaCl or 0.2 M Li 2 SO 4 at 13.85 °C showed similar results, with K G6PD ~ 0.46. The lowest partition coefficient was obtained in the presence of 0.5 M KI (K G6PD = 0.12), with major recovery of the enzyme in the micelle-dilute phase (%Recovery = 90%). Our results show that choosing the correct salt to add to ATPMS may be useful to attain the desired partitioning conditions at more extreme temperatures. Furthermore, this system can be effective to separate a target biomolecule from fermented broth contaminants.

Application of an aqueous two‐phase micellar system to extract bromelain from pineapple (Ananas comosus) peel waste and analysis of bromelain stability in cosmetic formulations

“…Their study demonstrated that knowledge of the electrolyte influence in this type of system is essential to perform partitioning studies. Furthermore, the correct choice of salt to be added can be pivotal to identify certain temperature conditions, thus allowing the achievement of more extreme or lower temperatures …”

“…Furthermore, the correct choice of salt to be added can be pivotal to identify certain temperature conditions, thus allowing the achievement of more extreme or lower temperatures. 45 In a study conducted by Amid and colleges, the effectiveness of different types and concentrations of nonionic surfactants (Pluronic series and X-114) on the partitioning behavior of the serine protease from kesinai leaves was evaluated. Their results showed that the enzyme preferentially partitioned into the bottom surfactant-rich phase.…”

Liquid–liquid extraction of lipase produced by psychrotrophic yeast Leucosporidium scottii L117 using aqueous two-phase systems

“…The %AB Lip of L. scottii L117 lipase ranged between 84.7% and 113% at 25.0 and 28.0°C in preliminary assays with the micellar system. An %AB Lip loss of 15% is considered acceptable in ATPS purification processes [31], therefore, we proceeded with our assessments using the nonionic surfactant TX-114 system for L. scottii L117 lipase extraction. The high 113.0% value may be related to a decrease in lipase inhibitor concentrations.…”

“…This affinity may be a reflection of hydrophobic interaction between micelle core and hydrophobic lipase surface [10]. In ATPMS, when the surfactant reaches a critical micelle concentration (CMC), micelles form in the aqueous solution following different geometric organizations such as lamellar, spherical, cubical, and planar [10,16,31], and polymeric system arrange themselves with different exclusion volume effect characteristics among system conditions and types. Therefore, polymeric and micellar system present different available volume to molecules partition.…”

“…During ATPS extraction, the pH can affect the charge of chemical groups present on amino acids side chains, modifying the net global charge of proteins. The number of charged groups on the protein molecule surface varies with pH, which results in modifications in protein structure and its intercalations with polymers and micelles [16,31].…”