Table 1. Reactivity of Canonical and Modified Nucleosides under the Photochemical Conditions.
| Entry | Starting material | Change in base-pairing propertiesa (%) |
|---|---|---|
| 1 | dA | n.d. |
| 2 | dG | n.d. |
| 3 | dT | n.d. |
| 4 | dC | 2.3 |
| 5 | d5mC | 2.3 |
| 6 | d5hmC | <1 |
| 7 | d5fC | <1 |
| 8 | d5caC | 99 |
a
Nucleoside concentrations calculated based on ratio of integrated UV–vis absorbance (260 nm) before and after 3 h incubations, relative to an internal dA standard. Reactions were repeated twice. n.d.: not detected (Figures S5–12, Table S2). Entries 5–8 represent the 2′-deoxynucleosides of 5-methylcytidine (d5mC), 5-hydroxymethylcytidine (d5hmC), 5-formylcytidine (d5fC), and 5-carboxycytidine (d5caC).