Development of bipyridine-modified nucleobase for methylcytosine-selective crosslink reaction

Recently, we have reported a novel epigenotyping method utilizing methylcytosine (M)-selective modification through osmium oxidation at a specific site of a long sequence using the formation of a bulge structure by hybridization with a guide DNA. In the key step of this chemical modification, the coordination of bipyridine ligand to osmium tetroxide accelerated the formation of a stable complex (M-Os-ligand). Herein, we report the development of novel capture oligodeoxy-nucleotides (ODNs) containing a bipyridine-modified nucleobase for M-selective interstrand crosslinking through cyclic osmate formation. The crosslink formation resulted in a drastic increase in the melting temperature (T(m)) of the duplex.