5-Methyl-2'-deoxyzebularine or m5K, is an intrinsically fluorescent nucleoside that, upon incorporation into oligonucleotides,⁽¹⁾ allows the characterization of the assembly of RecA-ssDNA complexes that initiate DNA repair responses.^1b Further, deletion of the C4 amino group of dC allows dissection of the roles of various hydrogen bonds, and the incorporation of 2-pyrimidinone residues into DNA allows the formation of abasic sites at selected positions after mild acid hydrolysis.⁽²⁾ See also a ribo version, Zebularine CE-Phosphoramidite (BA0254).

Ref:

1. (a) Gildea, B.; McLaughlin, L. W. Nucleic Acids Res. 1989, 17(6), 2261-2281. (b) Singleton, S. F. et al., Organic Lett. 2001, 3, 3919-3922.
2. Iocono, J. A.; Gildea, B.; McLaughlin, L. W.,Tetrahedron Lett. 1990, 31, 175-178.