Oxygen Dependence of Product Formation in Irradiated Adenosine 5′-Monophosphate

The formation of (R)- and (S)-8,5′-cycloadenosine 5′-monophosphate (8,5′-cycloAMP), 8-hydroxyadenosine 5′-monophosphate (8-hydroxyAMP), and radiolytic adenine release from irradiated solutions of adenosine 5′-monophosphate (5′-AMP) was measured as a function of increasing liquid-phase oxygen concentration. Three classes of specific molecular damage were identified on the basis of the oxygen dependence for product formation. Major changes in product yield occurred near the range of oxygen concentrations associated with the radiobiological oxygen effect. In addition to these data, systematic increases in the concentration of hydrogen peroxide at the time of irradiation resulted in an increase in the yield of 8-hydroxyAMP and a component of radiolytic adenine release in nitrogen-saturated solutions of 5′-AMP. However, no changes in the yield of the 8,5′-cyclonucleotides were observed under these conditions.