5AXE:
reference: Effect of an N-substituent in sulfonamide-bridged nucleic acid (SuNA) on hybridization ability and duplex structure., Mitsuoka Y, Aoyama H, Kugimiya A, Fujimura Y, Yamamoto T, Waki R, Wada F, Tahara S, Sawamura M, Noda M, Hari Y, Obika S, Org Biomol Chem. 2016 Jul 6;14(27):6531-8. doi: 10.1039/c6ob01051b. PMID: 27296230

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