Table 1.

Formation (+) or not (−) of 4 upon γ-irradiation of different nucleotide derivatives

Sample	Digestion	Formation of 4
γ-5′-CMP	P1 + Palk	−
γ-3′-dCMP	P1 + Palk	+
γ-pdCp	P1 + Palk	+
γ-3′-TMP + dCyd	P1 + Palk	+
γ-3′-TMP + dCyd	None	+

Formation of 4 was detected by HPLC-MS/MS after either digestion of the samples with both nuclease P1 and phosphatase alkaline (P1 + Palk) or in the absence of hydrolysis (None).