title: Features of the milk whey protein partitioning in polyethyleneglycol-sodium citrate aqueous two-phase systems with the goal of isolating human alpha-1 antitrypsin expressed in bovine milk.
abstract: Partitioning behaviour of the bovine whey proteins (bovine serum albumin, alpha-lactoalbumin and beta-lactoglobulin) and human alpha-1 antitrypsin in aqueous two-phase systems prepared with polyethyleneglycol (molecular masses: 1000, 1450 and 3350)-sodium citrate was analysed at pH 5.2, 6.2 and 8.2. Alpha lactoalbumin concentrated in the polyethyleneglycol rich-phase, while beta-lactoglobulin, bovine serum albumin and alpha-1 antitrypsin showed affinity for the citrate rich-phase. In aqueous two-phase systems of high medium pH and high polyethyleneglycol molecular mass the protein partitioning equilibrium is displaced to the citrate rich-phase. The polyethyleneglycol 1450-pH 5.2 system with a top/bottom phase-volume ratio of 3 showed to have the best capability of recovering the alpha-1 antitrypsin from a mixture prepared with natural milk whey and human alpha-1 antitrypsin. The recovery of this protein in the bottom phase was of 90% and the purity of the obtained product was of 98%. The method appears to be suitable as a starting point to isolate other human proteins expressed in transgenic bovine milk.
authors.affiliation: Chemical Physics Department, Bioseparation Lab., CONICET, and FonCyT, Faculty of Biochemical and Pharmaceutical Sciences, National University of Rosario, S2002LRK Rosario, Argentina.
authors.forename: Andrea
authors.initials: A
authors.lastname: Boaglio
authors.forename: Georgina
authors.initials: G
authors.lastname: Bassani
authors.forename: Guillermo
authors.initials: G
authors.lastname: Picó
authors.forename: Bibiana
authors.initials: B
authors.lastname: Nerli
mesh_terms: D000818:Animals; D002417:Cattle; D002951:Citrates / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000302:isolation & purification*; D008970:Molecular Weight; D011092:Polyethylene Glycols / Q000737:chemistry*; D011994:Recombinant Proteins / Q000302:isolation & purification; D000077559:Sodium Citrate; D000067816:Whey Proteins; D000515:alpha 1-Antitrypsin / Q000302:isolation & purification*
chemical_list: D002951:Citrates; D008894:Milk Proteins; D011994:Recombinant Proteins; D000067816:Whey Proteins; D000515:alpha 1-Antitrypsin; D000077559:Sodium Citrate; D011092:Polyethylene Glycols