PARTITIONING OF HYDROPHOBIC AMINO-ACIDS AND OLIGOPEPTIDES IN AQUEOUS 2-PHASE SYSTEM CONTAINING SELF-AGGREGATING BLOCK-COPOLYMER - EFFECTS OF TEMPERATURE, SALTS AND SURFACTANTS

The partitioning of hydrophobic amino acids and oligopeptides in the P luronic P105-dextran-water system has been studied. Pluronic P105 is a member of a family of triblock copolymers with the structure PEO-PPO- PEO, where PEO is poly(ethylene oxide) and PPO poly(propylene oxide). The partitioning was studied for tryptophan, phenylalanine and di- and tri-peptides composed of these amino acids at 5 and 40 degrees C. The se temperatures correspond to a unimeric (5 degrees C) and a micellar (40 degrees C) state of the P105 molecule. Partitioning depended stron gly on the temperature which is attributed to the increased hydrophobi city of Pluronic P105 with increasing temperature. However, it appears that the presence of the micelles plays no major direct role. The eff ect of different pH, salts and surfactants (both cationic and anionic) on partitioning has also been investigated.