title: Porcine pancreatic lipase partition in potassium phosphate-polyethylene glycol aqueous two-phase systems.
abstract: This research study examined porcine pancreatic lipase partition in aqueous two-phase systems formed by polyethylene glycol-potassium phosphate at pH 6.0, 7.0 and 8.0, the effect of polymer molecular mass, and NaCl concentration. The enzyme was preferentially partitioned into the polyethylene glycol rich phase in systems with molecular mass 4000-8000, while with polyethylene glycol of 10,000 molecular mass it was concentrated in the phosphate rich phase. The enthalpic and entropic changes found due to the protein partition were negative for all the polyethylene glycol molecular mass systems assessed. Both thermodynamic functions were shown to be associated by an entropic-enthalpic compensation effect suggesting that the water structure ordered in the ethylene chain of polyethylene glycol plays a role in the protein partition. The addition of NaCl increased the lipase affinity to the top phase and this effect was most significant in the system polyethylene glycol 2000-NaCl 3%. This system yielded an enzyme recovery more than 90% with a purification factor of approximately 3.4.
authors.affiliation: Bioseparation Lab, Physical-Chemistry Department, Faculty of Biochemical and Pharmaceutical Sciences, National University of Rosario, FonCyT, CIUNR and CONICET, Suipacha 570, S2002RLK Rosario, Argentina.
authors.forename: Georgina
authors.initials: G
authors.lastname: Bassani
authors.forename: Beatriz
authors.initials: B
authors.lastname: Farruggia
authors.forename: Bibiana
authors.initials: B
authors.lastname: Nerli
authors.forename: Diana
authors.initials: D
authors.lastname: Romanini
authors.forename: Guillermo
authors.initials: G
authors.lastname: Picó
mesh_terms: D000818:Animals; D006863:Hydrogen-Ion Concentration; D008049:Lipase / Q000302:isolation & purification*; D010179:Pancreas / Q000201:enzymology; D010710:Phosphates; D011092:Polyethylene Glycols; D017680:Potassium Compounds; D012995:Solubility; D013552:Swine; D013696:Temperature
chemical_list: D010710:Phosphates; D017680:Potassium Compounds; D011092:Polyethylene Glycols; C013216:potassium phosphate; D008049:Lipase