title: Optimization of conditions for acid protease partitioning and purification in aqueous two-phase systems using response surface methodology.
abstract: Aspergillopepsin I, an acid protease, was purified using an aqueous two-phase system that comprised various combinations of polyethylene glycol (PEG), NaH2PO4 and NaCl. Partition of the enzyme depended upon the molecular mass of the PEG and the presence of NaCl. With PEG 1500, 4000 and 6000, the partition coefficients were increased by 1,500-, 1,800- and 560-fold compared to values without NaCl. The presence of NaCl (8.75%, w/w) increased purification by 3.8, 9.5 and 2.8 times into these respective PEGs. The optimal aqueous two-phase system for acid protease purification was developed using response surface methodology. This system contained 17.3% of PEG 4000 (w/w), 15% NaH2PO4 (w/w) and 8.75% NaCl (w/w) and provided the best partition coefficient (Ke > 1,100) and yield over 99% in the same phase. The optimal ATPS purification factor of acid protease was over 5.
authors.affiliation: Department of Applied and Engineering Chemistry, Faculty of Technology, University of Novi Sad, Bulevar Cara Lazara 1, Novi Sad, Serbia.
authors.forename: Draginja M
authors.initials: DM
authors.lastname: Pericin
authors.forename: Senka Z
authors.initials: SZ
authors.lastname: Madarev-Popović
authors.forename: Ljiljana M
authors.initials: LM
authors.lastname: Radulović-Popović
mesh_terms: D000704:Analysis of Variance; D016282:Aspartic Acid Endopeptidases / Q000302:isolation & purification*; D001234:Aspergillus niger / Q000201:enzymology*; D001709:Biotechnology / Q000379:methods*; D008954:Models, Biological; D008970:Molecular Weight; D011092:Polyethylene Glycols / Q000494:pharmacology; D015203:Reproducibility of Results; D012965:Sodium Chloride / Q000494:pharmacology; D013499:Surface Properties / Q000187:drug effects
chemical_list: D011092:Polyethylene Glycols; D012965:Sodium Chloride; D016282:Aspartic Acid Endopeptidases; C029094:aspergillopepsin I