ABSORPTION AND FLUORESCENCE BEHAVIOR OF CYTOSINE IRRADIATED AT DIFFERENT PH AND IN THE PRESENCE OF CU(II) IONS AT NEUTRAL PH

Dilute aqueous solutions of cytosine were irradiated with Co-60 gamma- rays under N2O saturated conditions at different pH and in the presenc e of Cu(II) ions at neutral pH. The base degradation decreased from ne utral to acidic and basic conditions. In the presence of metal ions at neutral pH conditions there was a significant increase in the base de gradation compared to that in the absence of metal ions under similar conditions. From the difference absorption spectra and fluorescence be havior of the irradiated solutions it was observed that the major radi olytic products of cytosine under different conditions are cytosine gl ycols, 5-hydroxycytosine, hydroxy-hydrocytosine and cytosine dimers. T he yields of dimers is maximum in neutral conditions and it decreased from basic to acidic conditions. However, in the presence of Cu(II) io ns formation of cytosine dimers is completely restricted and there is an increase in the yields of cytosine glycol, hydroxy-hydrocytosine an d 5-hydroxycytosine. From the post-radiolytic changes in absorption an d fluorescence behavior of irradiated solutions, it is revealed that s ome of the radiolytic products, namely cytosine glycol and hydroxy-hyd rocytosine decompose to 5-hydroxycytosine and cytosine, respectively.