The molecule is a single-stranded DNA oligonucleotide composed of five deoxythymidylic acid residues connected by 3'->5' phosphodiester linkages and terminated by 3'- and 5'-phosphate groups.
[(2R,3S,5R)-2-[[hydroxy-[(2R,3S,5R)-2-[[hydroxy-[(2R,3S,5R)-2-[[hydroxy-[(2R,3S,5R)-5-(5-methyl-2,4-dioxopyrimidin-1-yl)-2-(phosphonooxymethyl)oxolan-3-yl]oxyphosphoryl]oxymethyl]-5-(5-methyl-2,4-dioxopyrimidin-1-yl)oxolan-3-yl]oxyphosphoryl]oxymethyl]-5-(5-methyl-2,4-dioxopyrimidin-1-yl)oxolan-3-yl]oxyphosphoryl]oxymethyl]-5-(5-methyl-2,4-dioxopyrimidin-1-yl)oxolan-3-yl] [(2R,3S,5R)-5-(5-methyl-2,4-dioxopyrimidin-1-yl)-3-phosphonooxyoxolan-2-yl]methyl hydrogen phosphate