Fig. 4. Nitrite-mediated deamination of methylated nucleosides. (a) HPLC analysis of the conversion of m⁶A into nitrosylated m⁶A (m⁶A-NO) using NaNO₂ and 1.7% aqueous AcOH, at 22 °C over 3.5 h. m⁶A-NO was confirmed by ESI-MS. Note that inosine was not detected by HPLC analysis of nitrosylation of m⁶A. No reaction was observed over a 12 h period for (b) m¹A or (c) m³C.