Comparative free radical chemistry in the radiolytic deamination and dephosphorylation of bio-organic molecules. II. Oxygenated solutions.

The radiolytic deamination and dephosphorylation of peptides and phosphate esters in oxygenated solutions are OH-induced and involve the formation and subsequent degradation of the peroxyl radicals RCONHC(O2)R2 and POC(O2)R2 respectively. Reaction analogues in the degradation chemistry of these peroxyl intermediates from various peptides and phosphate esters including protein and DNA are evaluated in detail. The evidence is that the reaction mechanisms recently proposed for removal of POC(O2)R2 radicals in the radiolytic scission of the DNA strand are identical in form with the mechanisms identified in earlier studies of RCONHC(O2)R2 radicals in the radiolytic cleavage of the peptide chain. The analogy includes the chemical forms of the final products and their specific yields.