Characterization of a 5 '-aldehyde terminus resulting from the oxidative attack at C5 ' of a 2-deoxyribose on DNA

The 5'-aldehyde terminus is a DNA oxidative damage resulting from attack at C5' of 2-deoxyriboses by some potent natural or chemical DNA cleavers. To offer a fast and specific method for characterization of this type of damag e, we used on-line electrospray ionization mass spectrometry (ESI-MS) detec tion during liquid chromatography analyses. The intrinsic reactivity of 5'- aldehyde terminus with nucleophiles (formation of hydrate with water, of a Tris adduct with Tris buffer) or through beta -elimination reaction resulte d in complex LC profiles and MS data. We showed that derivatization of the aldehyde function as an oxime ether gives a stable derivative easy to chara cterize during on-line ESI-MS analyses. Complete structural characterizatio n of the Tris adduct and the oxime ether derivative were obtained from MS a nd detailed NMR studies performed on derivatized 5'-aldehyde thymidine mode ls.