Peptides partitioning in an aqueous dextran-polyethylene glycol two-phase system

Partitioning of glycine, lysine and aspartic acid and their oligopeptides i n an aqueous dextran-polyethylene glycol two-phase system containing 0.15 M NaCl in 0.01 sodium phosphate buffer, pH 7.3 and 0.11 M sodium phosphate b uffer, pH 7.3 was examined. Relative hydrophobicity of the amino acid resid ues and peptide bonds was estimated and expressed in equivalent numbers of methylene units. Analysis of a series of reversed di- and tripeptides in te rms of relative hydrophobicity showed that the additivity principle does ho ld for the hydrophobicity of short peptides. The relative hydrophobicity of peptides is affected by the ionic composition of aqueous media as well as by the type of amino acid residues forming peptide bonds in a given peptide sequence. (C) 2000 Published by Elsevier Science B.V. All rights reserved.