Hydrophobic interaction between tryptophan and some synthetic nucleosides.

The interaction of 29 synthetic nucleosides with tryptophan was studied by charge-transfer reversed-phase thin-layer chromatography and the relative strength of interaction was calculated. In the majority of cases Trp significantly decreased the lipophilicity of the nucleosides. This effect may be due to the interaction between the more hydrophilic Trp and the more lipophilic nucleosides, resulting in charge-transfer complexes of moderate lipophilicity. Stepwise regression analysis proved that the length of the alkyl substituent of nucleosides significantly influences the strength of interaction. Our findings supports the hypothesis that the nucleosides turn toward Trp with their alkyl substituent and the binding is of hydrophobic character.