Molecule of the Week

Isocytosine

June 7, 2010

Isocytosine (2-aminouracil) is a non-natural nucleobase and an isomer of one of the four main bases in DNA and RNA. It pairs in a “reversed Watson–Crick” manner with natural guanine or in a normal manner with non-natural isoguanine. In aqueous solution, it exists as two tautomers, the one shown and the other with a proton on the ring nitrogen opposite the carbonyl group.