The molecule is a single-stranded DNA polynucleotide consisting of a repeating unit of thymidine and 5-methyldeoxycytidine residues, with all residues connected by 3'->5' phosphodiester linkages.
[(2R,3S,5R)-5-(4-amino-5-methyl-2-oxopyrimidin-1-yl)-3-hydroxyoxolan-2-yl]methyl [(2R,3S,5R)-5-(5-methyl-2,4-dioxopyrimidin-1-yl)-2-(phosphonooxymethyl)oxolan-3-yl] hydrogen phosphate