Rotaxane-type resorcinarene tetramers as histone-sensing fluorescent receptors

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 ( and , respectively), were prepared. Rotaxane-type receptors and bound histone, a small basic protein component of eukaryotic chromatins, with binding constants of 2.3 x 10(6) and 9.0 x 10(5) 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 and the rhodamine residues of took place in the presence of histone, which was a useful method for the detection of histone.