Product ion studies of some novel arylamine adducts of deoxyguanosine by matrix-assisted laser desorption/ionization and post-source decay

The product ions of the BH2+ ions formed by the glycosidic cleavage of N-(d eoxyguanosin-O-6-yl)-2-methylaniline, 4-(deoxyguanosin-8-yl)-2-methylanilin e, and N-(deoxyguanosin-1-yl)-2-methylaniline have been studied using matri x-assisted laser desorption/ionization (MALDI) and post-source decay (PSD) to identify fragment ions and pathways that may be used to differentiate th eir structures. All three isomers may be distinguished based on their PSD p roduct ion spectra using only femtomole quantities of sample, N-(Deoxyguano sin-O-6-yl)-2-methylanaine produces product ions at m/z 107 and 134 that ar e diagnostic for 2-methylaniline attachment to the O-6 position of guanine. The BH2+ ion from 4-(deoxyguanosin-8-yl)-2-methylaniline yields a product ion Formed by the consecutive losses of 17 and 42 u neutral fragments that may be regarded as specific for guanine-arylamine adducts that possess two primary amine groups. The BH2+ ion from 4-(deoxyguanosin-8-yl)-2-methylanil ine yields no product ions that correlate with specificity for guanine N1 s ubstitution, However, the product ion abundance ratio of the protonated ary lamine to that of the ammonia loss ion may be used to differentiate an addu ct formed by N1 substitution from other arylamine adducts of guanine studie d thus far. Copyright (C) 1999 John Wiley & Sons, Ltd.