Box, H. C., Patrzyc, H. B., Dawidzik, J. B., Iijima, H., Freund, H. G., Higbee, A. J. and Budzinski, E. E. Detection and Characterization of Formamido Lesions in DNA by Liquid Chromatography-Mass Spectrometry. Radiat. Res. 158, 538–542 (2002).

DNA X-irradiated in oxygenated aqueous solution produces the formamido lesion from the breakdown of pyrimidine nucleosides. This pyrimidine breakdown product inhibits the hydrolysis by nuclease P1 of the phosphoester bond 3′ to the damaged nucleoside. Consequently, the lesion can be obtained from an enzymatic digest of the DNA as a modified dinucleoside monophosphate in which the 5′ nucleoside contains the lesion. In this form, the formamido lesion can be detected with good sensitivity by liquid chromatography-mass spectrometry (LC-MS). Nucleosides that have lost the base moiety also inhibit nuclease P1. Together, the formamido and abasic lesions account for all of the substantial peaks in the LC-MS ion current profile.