Pancreatic serine protease extraction by affinity partition using a free triazine dye

Affinity partitioning combines the partitioning behavior of biological macromolecules in aqueous two-phase systems with the principle of biorecognition. Among the numerous substances that have been evaluated as ligands, the reactive dyes constitute a group of low cost textile dyes which have proved to act as biomimetic ligands for many enzymes. The ability of reactive yellow 2 (RY2) to interact with trypsin (TRP) and chymotrypsin (ChTRP) and its behavior in aqueous two-phase systems formed by polyethylene glycol (PEG) and sodium citrate (NaCit) - were investigated. Different variables such as PEG molecular weight, tie line length and dye concentration were analyzed. RY2 showed to bind specifically to both TRP and ChTRP with affinity constants near to 10(3) M-1. Its partition equilibrium is practically displaced to the top phase in systems formed by PEG of different molecular weight. Addition of this dye to PEG 8000/NaCit systems until a final concentration of 0.196% (w/w) induced an increase in TRP and ChTRP partition coefficients of at least 2 times over that in the absence of the ligand. These findings demonstrate that RY2 fulfils all the requirements to be considered as an affinity ligand in aqueous two-phase partitioning of TRP and ChTRP. (C) 2011 Elsevier B.V. All rights reserved.