Generic application of an aqueous two-phase process for protein recovery from animal blood

The recovery of proteins from animal blood using an established two-stage e xtraction process was selected as a practical model system to study the gen eric application of polyethylene glycol (PEG)-phosphate aqueous two-phase s ystems (ATPS). Processing of whole bovine blood in the ATPS two-stage proce ss resulted in the partition of soluble protein (e.g. bovine serum albumin (BSA), haemoglobin, IgG; partition coefficient K = 55) into a PEG-rich top phase and cell debris into a phosphate-rich bottom phase. Subsequent back e xtraction of soluble protein into a second phosphate-rich bottom phase resu lted in a maximum overall protein recovery of 62%. The increased protein co ncentration within the ATPS (from 1.2 to 7.0 mg/g) caused a decreased in th e recovery to 44%. Recycling of PEG into the initial extraction stage did n ot significantly influence the partition behaviour of protein over the equi valent of 20 operational cycles, but protein recovery decreased from 44 to 37%. The extreme conditions (waste material characterised by the presence o f solids and impurities) in which the implementation of this ATPS process w as tested, confirms the potential for the generic application of ATPS for p rocessing complex biological suspensions to achieve a simple primary recove ry and partial purification of target protein solutes. (C) 2000 Elsevier Sc ience Ltd. All rights reserved.