Self-Aggregating Deep Cavitand Acts as a Fluorescence Displacement Sensor for Lysine Methylation

Abstract

A dual-mode aggregative host:guest indicator displacement sensing system has been created for the detection of trimethylated peptides and determination of histone demethylase activity. The combination of selective recognition of suitably sized trimethylammonium salts and reversible lipophilic aggregation of the host:guest complex provides a unique quenching mechanism that is not only dependent on affinity for sensitivity but the lipophilicity of the indicator. In addition, aggregation can be controlled by the application of chaotropic anions in the mixture, allowing a second level of discrimination between hard lysine groups and softer trimethyllysines.

Site-Selective Sensing of Histone Methylation Enzyme Activity via an Arrayed Supramolecular Tandem Assay

“…We have previously shown that the combination of cavitand 1 and a suitable fluorophore allows sensing of Kme 3 peptides via FDA. 15 This concept can be extended to allow site-selective Kme 3 recognition by the application of cavitands 1–3 in an array-based format, 16 followed by discrimination via principal component analysis (PCA). 17 The sensor can discriminate Kme 3 residues at different positions on peptides, and even sense remote changes in peptide structure.…”

“…17 The sensor can discriminate Kme 3 residues at different positions on peptides, and even sense remote changes in peptide structure. The sensitivity of the system to methylation site 16 and state 15 suggests that it would be capable of site-selective monitoring of methylation enzyme activity (Figure 1). …”

Site selective reading of epigenetic markers by a dual-mode synthetic receptor array

“…Evidently 13 also forms micelles, which incorporate the 2·4 complex, causing additional aggregation-based quenching of 4 . 26 While unexpected, this phenomenon provides another variable for discrimination of lipophilic guests, one that is not dependent on cavity-based recognition.…”

“…26 The binding of fluorescein guest 5 in host 1 causes aggregation of the lipid-like host (Fig. 1b) and concomitant aggregation-based quenching of the guest.…”

“…Fluorescence recovery occurs upon displacement of 5 by the desired KMe 3 target. 26 While this sensing system was effective for discriminating between histone KMe 3 and KMe 0/1/2 , the more challenging task of site-selective discrimination requires more variables, and so we synthesized the simple rhodamine B variant, guest 4 . Guest 4 was synthesized from nitro-rhodamine B in two steps (see ESI† for procedures and characterization).…”