The interaction of the anionic surfactant sodium dodecylsulfate (SDS) with arginine, histidine, lysine, ornithine and tryptophan was studied by using reversed-phase thin-layer chromatography on unimpregnated cellulose layers. The relative strength of interaction and the impact of salt concentration and pH on it was calculated by using stepwise regression analysis. SDS did not interact with His, and its interaction with Trp was fairly weak. SDS strongly binds to dibasic amino acids; the relative strength of interaction is significantly higher with Lys and Orn than with Arg. These results indicate that SDS probably binds to the secondary amino groups of Lys in proteins. The impact of sodium chloride and acetic acid was similar, but the effect of sodium acetate was significantly weaker. The strong dependence of the strength of interaction on the salt concentration and on the pH of the eluent indicates that hydrophilic, probably electrostatic forces are involved in the SDS-protein interaction.
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