CHARGE-TRANSFER CHROMATOGRAPHIC STUDY ON THE INTERACTION OF AMINO-ACIDS WITH ETHOXYLATED STEARIC-ACID SURFACTANTS

The interaction of amino acids with ethoxylated stearic acid nonionic surfactants was studied by charge-transfer reversed-phase thin-layer c hromatography and the relative strength of interaction was calculated. In the majority of cases the surfactant has a negligible effect on th e hydrophobicity of amino acids. Only the binding of Asn, Cys, Gln, Le u, Lys, Met, Nle, Phe, Ser, Trp and Tyr to the surfactants was observe d, however, the strength of interaction was fairly low. Stepwise regre ssion analysis proved that the electronic parameters of the amino acid s have the highest impact on the strength of interaction. This finding supports the hypothesis that the binding of ethoxylated stearic acid nonionic surfactants to proteins involves more than one amino acid res idues and that the hydrophilic forces have a considerable impact on th e interaction.