The molecule is a single-stranded DNA oligonucleotide consisting of two thymidine molecules linked (3'->5') and also with a C6-C4 bond. It results from irradiation at 254 nm of normal dTpT (PDB entry: 1EHL).
(2R,4S,5R,10S,11R,13R,18R,19S)-4,8,18-trihydroxy-11-(hydroxymethyl)-18,24-dimethyl-8-oxo-7,9,12,26-tetraoxa-1,14,16,21-tetraza-8lambda5-phosphapentacyclo[18.2.2.12,5.110,13.014,19]hexacosa-20,23-diene-15,17,22-trione