title: The influence of major components on the direct chromatographic recovery of a protein from transgenic milk.
abstract: This work presents a systematic evaluation of the influence of lipids and casein on the performance of a chromatographic capture step for the recovery of a target protein from transgenic milk. Lactoperoxidase (LPO) was spiked at concentrations typical of those to be expected for transgenic proteins in commercial bovine milk and the dynamic adsorption of LPO to fixed beds of SP Sepharose FF studied in frontal analysis experiments. By removing successively selected components from whole milk, their individual influence on the dynamic adsorption behaviour of LPO could be studied. A mathematical model, fitted to the breakthrough curves of LPO, provided a quantitative measure of parameters describing mass transfer and adsorption in the column. A significant reduction in column capacity for LPO in the presence of milk or whey was recorded, which could be attributed to competing adsorption of alkaline earth metal ions to the cation exchange resin. While the high concentrations of lipids present in whole milk did strongly reduce the column permeability, no significant influence of either casein or low concentrations of lipids on the hydraulic properties of columns or on the adsorption of LPO could be detected. The results indicate that chromatography, which forms an essential part of all current large-scale processes for the recovery of proteins from transgenic milk, could potentially be moved further upstream. Alternatively, existing operations for the removal of lipid and casein could be re-designed so as to maximise product yields. This suggests that significant product losses during current pre-chromatography milk purification could be reduced or potentially even avoided.
authors.affiliation: The Advanced Centre for Biochemical Engineering, University College London, Torrington Place, London WC1E 7JE, UK.
authors.forename: Lars
authors.initials: L
authors.lastname: Pampel
authors.forename: Rihab
authors.initials: R
authors.lastname: Boushaba
authors.forename: Mike
authors.initials: M
authors.lastname: Udell
authors.forename: Mike
authors.initials: M
authors.lastname: Turner
authors.forename: Nigel
authors.initials: N
authors.lastname: Titchener-Hooker
mesh_terms: D000327:Adsorption; D000818:Animals; D030801:Animals, Genetically Modified; D002364:Caseins / Q000737:chemistry; D002853:Chromatography, Liquid / Q000379:methods*; D007784:Lactoperoxidase / Q000737:chemistry; D008055:Lipids / Q000737:chemistry; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000302:isolation & purification*; D013816:Thermodynamics
chemical_list: D002364:Caseins; D008055:Lipids; D008894:Milk Proteins; D007784:Lactoperoxidase