Cytidine absorption spectra

The resulting heteroatom-protonated electron adduct(s) must have a value > 11, as shown by conductance measurements in pulse radiolysis [56]. The absence of any noticeable change in the absorption spectrum of the (protonated) electron adduct of cytidine in the pH range 6-13 suggests that its p a value is even larger than 13 [60]. Like the situation in the corresponding thymine system, the heteroatom-protonated species is thermodynamically disfavoured and subsequent (irreversible) protonation occurs at carbon [reaction (63)], albeit with a rate constant too low [61] to be measured by pulse radiolysis. 

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