Furan-based click and photo-click reactions for nucleic acid modification

Within OBCR, we have developed a highly selective and efficient singlet oxygen mediated crosslink technology which is applicable to peptide-protein, peptide-nucleic acid and nucleic acid interstrand crosslink scenarios.[1] For this purpose, a furan ‘warhead’ is introduced into one of the biomolecular partners and subsequently activated by means of an oxidation trigger such as singlet oxygen which induces generation of a nucleophile-sensitive keto-enal moiety.[2] The overall procedure allows spatiotemporal control of the crosslinking event. Furan-modified oligonucleotide probes were designed for efficient and selective crosslinking to natural nucleic acid targets,[3] including the elusive G-quadruplex and I-motif targets.[4] Introduction of a slighly modified furan moiety into peptides and peptide nucleic acids (PNAs) allowed development of a triggerless proximity-induced click ligation with applications in nucleic acid biomarker detection and protein array design[5] as well as peptide cyclisation.[6] Furthermore, we have developed a robust secondary structure stapling methodology by incorporating a variety of previously designed DNA crosslinking moieties in several tetraplexed systems. The benefits of such stapling approach include an increased melting temperature and exonuclease resistance with no loss of biological activity. Crucially, a steric lock is created that allows the secondary structure to resist external influences on its topology.[7]