Specific Extraction of Aspartic Acid and Tyrosine with Aqueous Two-phase Systems Formed by Hydrophilic Organic Solvent and Monomeric Sugars

An aqueous two-phase system (ATPS) formed by hydrophilic organic solvent and sugars is environmentally benign and has the advantages of fast phase separation. We carried out the distribution of amino acids in an ATPS formed by hydrophilic organic solvents (2-methyl-2-propanol, tetrahydrofuran, and 2-propanol) and sugars (glucose and fructose). From the binodal curves and the distribution of dinitrophenyl amino acids, in term of the hydrophobic effect, ATPS formed by tetrahydrofuran and glucose was a better media for amino acid separation. The most amino acids were successfully extracted using combination of solvents and sugars. The distribution ratio of amino acids increases with increasing the hydrophobicity of the amino acids, except for those of aspartic acid and tyrosine. The specific extractions of aspartic acid and tyrosine were caused by the aggregation between these amino acids and sugars.