Reduction-Responsive DNA Duplex Containing O(6)-Nitrobenzyl-Guanine

[Image: see text] Stimuli-controlled structural transitions of nucleic acids have received growing attentions owing to their potential applications in the fields of chemical and synthetic biology. Here, we describe the development of reduction-responsive deoxyribonucleic acid (DNA) duplexes, in which guanine rings bearing a reduction-responsive cleavable nitrobenzyl (NB) group at the O(6) position (G(NB)) are introduced at defined positions. We demonstrate that the artificial NB group can be removed in response to reduction stimulus without the dissociation of the intermolecular duplex structure, which comprises a G-quadruplex forming nucleic acid strand with one G(NB) and its complementary sequence with one mismatch pair. Meanwhile, another duplex that comprised a G-quadruplex forming nucleic acid strand with two G(NB) and its complementary sequence with three mismatch pairs exhibited reduction-responsive structural transitions from intermolecular duplex to intramolecular quadruplex. These findings might be useful for the development of DNA architectures endowed with reduction-responsive functions.