Partition of whey milk proteins in aqueous two-phase systems of polyethylene glycol-phosphate as a starting point to isolate proteins expressed in transgenic milk

CAPEZIO, LORENA; ROMANINI DIANA; PICÓ GUILLERMO; NERLI BIBIANA

Journal of Chromatography B

Elsevier Science Ireland Ltd

Año: 2005 vol. 819 p. 25 - 31

1570-0232

Partitioning behaviour of the bovine whey proteins (bovine serum albumin, alpha lactoalbumin and beta lactoglobulin) and alpha-1 antitrypsin in aqueous two-phase systems prepared with polyethyleneglycol (molecular mass 1,000; 1,500 and 3,350)-potassium phosphate was analysed. Bovine serum albumin and alpha lactoalbumin concentrated in the polyethyleneglycol rich phase with a partition coefficient of 10.0 and 27.0 respectively, while beta lactoglubulin and alpha-1 antitrypsin showed affinity for the phosphate rich phase with a partition coefficient of 0.07 and 0.01 respectively. An increase of medium pH induced an increase of the partition coefficient of these proteins while the increase in polyethyleneglycol molecular mass induced the opposite behaviour. The system polyethyleneglycol 1500- pH 6.3 showed the best capacity for recovering the alpha-1 antitrypsin with a yield of 80 % and a purification factor between 1.5 and 1.8 from an artificial mixture of the milk whey proteins and alpha-1 antitrypsin. The method appears to be suitable as a starting point to isolate proteins expressed in transgenic milk.