Extraction of trypsin from bovine pancreas by applying polyethyleneglycol/sodium citrate aqueous two-phase systems

The goal of this work was to determine the optimal conditions for separating trypsin (TRP) from alpha-chymotrypsin (ChTRP) and to apply them for trypsin purification from bovine pancreas by liquid–liquid extraction with polyethyleneglycol/sodium citrate (PEG/NaCit) aqueous two-phase systems. Partitioning behaviours of TRP and ChTRP are demonstrated to be very sensitive to variables such as PEG molecular weight, pH and tie line length. Aqueous two-phase systems (ATPSs) formed by PEG of MW 3350 and NaCit pH 5.20 showed the best separation capability. The addition of NaCl up to a final concentration of 7% (w/w) and the decrease of top/bottom volume ratio to 0.1 led to the recovery of 60% of pancreatic TRP in a concentrated form in the top phase with a 3-fold purification. Biomass presence up to 25% (w/w) of the total system mass did not affect significantly yield and purification parameters.