DIRECT EFFECT OF HEAVY-IONS AND ELECTRONS ON 2'-DEOXYGUANOSINE IN THESOLID-STATE

Attempts have been made in this work to gain insights into the mechani sms of the formation of degradation products arising from the exposure of 2'-deoxyguanosine (dGuo) in the solid state to O7+ heavy ions of 1 0.6 MeV u(-1) (LET approximate to 500 keV mu m(-1)). The main decompos ition products of dGuo have been isolated by reversed-phase high perfo rmance liquid chromatography and characterized by extensive spectrosco pic (H-1 and C-13 NMR, mass spectrometry, UV) measurements. Reaction m echanisms, involving the transient formation of sugar and purine radic al, are proposed to explain the generation of the heavy ion-mediated d egradation products. Another major objective of the present work is th e comparison of heavy ion-induced modifications of 2'-deoxyguanosine w ith those produced by lower LET radiation. For this purpose, the sampl es of 2'-deoxyguanosine were exposed in the solid state to electrons o f 2 MeV (LET approximate to 0.18 keV mu m(-1)). It may be inferred fro m the results of the qualitative and semi-quantitative comparison that the modifications of the sugar moiety are more efficiently induced by heavy ions than by electrons.