Partitioning of whey proteins, bovine serum albumin and porcine insulin inaqueous two-phase systems

Partitioning of the proteins from cheese whey, bovine serum albumin and por cine insulin were analysed using aqueous two-phase systems (ATPS) prepared with PEG-phosphate, PEG-citrate and PEG-maltodextrin (MD). Proteins were qu antified through one of the following methods: FPLC, Bradford and spectroph otometry at 280 nm. Results showed that whey proteins partitioned unevenly on the phases of the systems used, with alpha-lactoalbumin (alpha-La) conce ntrated in the upper phase and beta-lactoglobulin (beta-Lg) in the lower. A lbumin in PEG-MD systems concentrated in the MD-rich lower phase. Porcine i nsulin showed great affinity with the PEG-rich phase, its partition coeffic ient was always over 10 and increases with PEG molecular mass. (C) 2000 Els evier Science B.V. All rights reserved.