Interaction of Hydroxypropyl- b-Cyclodextrin with Peptides, Studied by Reversed-Phase Thin-Layer Chromatography

The effect of various concentrations of hydroxypropyl-b-cyclodextrin (HPb-CD) on the reversed-phase thin-layer chromatographic mobility of some low molecular mass peptides was measured in distilled water and in 0.05 M of LiCl, NaCl, KCl, RbCl, and CsCl solutions, and the relative strength of HP-b-CD–peptide interaction has been calculated from the dependence of retention on the concentration of HP-b-CD in the mobile phase. Lipophilicity of the peptides decreased regularly with increasing concentration of HP-b-CD in the mobile phase, proving the interaction (probably the formation of inclusion complexes) between peptides and HP-b-CD. Principal component analysis indicated that each salt influenced the interaction differently. Peptides formed clusters on the two-dimensional nonlinear map according to the character of the amino acid monomer and not according to the number of amino acid units, suggesting that only one terminal amino acid is included in the cavity of HP-b-CD.