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Isoguanine or 2-hydroxyadenine is a purine base that is an isomer of guanine. It is a product of oxidative damage to DNA and has been shown to cause mutation.[1] It is also used in combination with isocytosine in studies of unnatural nucleic acid analogues of the normal base pairs in DNA.[2][3]

Isoguanine vector.svg
IUPAC name
Other names
3D model (JSmol)
ECHA InfoCard 100.020.144
EC Number
  • 222-157-6
Molar mass 151.1261
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

It is used as a nucleobase of hachimoji nucleic acids.[4] In hachimoji DNA, it pairs with 1-methylcytosine, while in hachimoji RNA, it pairs with isocytosine.



  1. ^ Yang XL, Sugiyama H, Ikeda S, Saito I, Wang AH (1998). "Structural studies of a stable parallel-stranded DNA duplex incorporating isoguanine:cytosine and isocytosine:guanine basepairs by nuclear magnetic resonance spectroscopy". Biophys. J. 75 (3): 1163–1171. doi:10.1016/S0006-3495(98)74035-4. PMC 1299791. PMID 9726918.
  2. ^ Andrzej Jaworski, Józef S. Kwiatkowski, Bogdan Lesyng: „Why isoguanine and isocytosine are not the components of the genetic code", International Journal of Quantum Chemistry, Supplement: Proceedings of the International Symposium on Quantum Biology and Quantum Pharmacology, 1985, 28 (Supplement S12), pp. 209–216 (doi:10.1002/qua.560280720).
  3. ^ Christopher Roberts, Rajanikanth Bandaru, Christopher Switzer: „Theoretical and Experimental Study of Isoguanine and Isocytosine:  Base Pairing in an Expanded Genetic System", J. Am. Chem. Soc., 1997, 119 (20), pp. 4640–4649 (doi:10.1021/ja970123s).
  4. ^ Hoshika, Shuichi; et al. (22 February 2019). "Hachimoji DNA and RNA: A genetic system with eight building blocks". Science. 363 (6429): 884–887. doi:10.1126/science.aat0971.