ExciTides: NTP-derived probes for monitoring pyrophosphatase activity based on excimer-to-monomer transitions

We describe a new type of nucleotide-derived fluorescent probe designed for monitoring pyrophosphatase activity based on excimer-to-monomer transitions, called ExciTide. The nucleotides were designed with two self-interacting dye moieties and synthesised using copper-catalysed azide–alkyne cycloaddition click chemistry. We applied these probes for enzyme activity monitoring and inhibitor evaluation. Some of the probes permeated into living cells, yielding interesting prospects for future applications.