Nitric oxide (NO) produced in inflamed tissues is known to cause DNA damage by nitrosation or oxidation of base moieties. For investigating the biophysical and biochemical properties of DNA lesions induced by nitric oxide, we prepared synthetic DNA oligomers and analyzed melting temperature (T(m)) or enzymatic recognition of DNA strands containing oxanine (Oxa) and hypoxanthine (Hyp), using guanine (Gua) or adenine (Ade) as control bases, respectively. For enzymatic reaction by DNA-relevant enzymes, we employed T4 polynucleotide kinase, T4 DNA ligase and DNA polymerase (Klenow fragment (exo-)). These analyses revealed that enzymatic recognition of Oxa:Cyt or Hyp:Thy were almost same as Gua:Cyt or Ade:Thy in DNA strands, respectively, indicative of similar molecular and biological recognition of DNA-lesions to normal DNA bases in the cell.