Rotaxane-type resorcinarene tetramers as histone-sensing fluorescent receptors

Abstract

Rotaxane-type receptors, which were composed of anionic cyclophane-based resorcinarene tetramers as the wheel and a 2,6-disubstituted naphthalene derivative having two fluorophore moieties, such as fluorescein and rhodamine residues, as the axle (1 and 2, respectively), were prepared. Rotaxane-type receptors 1 and 2 bound histone, a small basic protein component of eukaryotic chromatins, with binding constants of 2.3 × 10⁶ and 9.0 × 10⁵ M⁻¹, respectively. The rotaxane-type receptors showed fluorescence sensing ability with remarkable histone selectivity. Moreover, fluorescence resonance energy transfer (FRET) between the fluorescein residues of 1 and the rhodamine residues of 2 took place in the presence of histone, which was a useful method for the detection of histone.