Partition coefficients of amino acids, peptides, and enzymes in dextran plus poly(ethylene glycol) plus water aqueous two-phase systems

Partition coefficients are measured for five amino acids (aspartic acid, as paragine, methionine, cysteine and histidine) and two peptides (glycyl-glyc ine and hexa-glycine) in dextran + poly(ethylene glycol)+ water aqueous two -phase system. The partition coefficients of the amino acids and peptides a re correlated using the osmotic virial equation. The interaction coefficien ts contained in the equation can be calculated by hydrophilic group paramet ers. The partition coefficients of alpha-amylase calculated by the osmotic virial equation with the hydrophilic group parameters are in fairly good ag reement with the experimental data, though a relatively large discrepancy i s shown for beta-amylase.