Partitioning of hydrophobic amino acids and oligopeptides in aqueous two-phase system containing self-aggregating block copolymer effects of temperature, salts and surfactants

Abstract

The partitioning of hydrophobic amino acids and oligopeptides in the Pluronic 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°C. These temperatures correspond to a unimeric (5°C) and a micellar (40°C) state of the P105 molecule. Partitioning depend strongly on the temperature which is attributed to the increased hydrophobicity of Pluronic P105 with increasing temperature. However, it appears that the presence of the micelles plays no major direct role. The effect of different pH, salts and surfactants (both cationic and anionic) on partitioning has also been investigated.