The Mechanism of Chromatographic Retention - Chromatographic Interactions > Ionic Interactions > Page 19

The only polar groups are the peptide bonds themselves and the two aromatic rings from the phenylalanine fragments that could produce induced dipoles. It follows that the overall characterof the hexapeptide is likely to be dispersive and thus the peptide would be described as hydrophobic or lyophobic in nature.

In contrast the peptide shown in figure 8 might be considered to be the heptapeptide,


or of similar composition. In this peptide there is a preponderance of polar groups; e.g., hydroxyl groups contributed by the two serine and threonine fragments, the amino and carbamidine groups from thearginine and threonine together with the peptide bonds themselves. The very short aliphatic chains contributed by glycine fragments (CH2 groups) will only provide weak dispersive interactions.


Figure 8. Examples of a Hydrophilic Peptide