Table 1.
Enthalpies of activation for cytosine deamination
| Cytosine derivative (ref) | ΔH‡ (kcal/mol) | pH | Method | Temperature (°C) | No. points |
| Cytarabine (38) | 16.4 | 6.9 | UV | 24–47 | 4 |
| Cytosine (21) | 11.6 | 7.0 | UV | 70–90 | 4 |
| Cytidine (21) | 12.4 | 7.0 | UV | 70–90 | 4 |
| dCMP (21) | 28.4 | 7.4 | UV | 70–95 | 3 |
| ssDNA (21) | 28.4 | 7.4 | 14C chromat. | 70–95 | 3 |
| ssDNA (22) | 27.4 | 7.4 | Reversion | 30–90 | 13 |
| Cytidine (39) | 22.1 | 6.8 | UV | 80–157 | 9 |
| 2'-Deoxycytidine (37) | 24.8 | 6.8 | 1H-NMR | 90–137 | 6 |
| 1-Methylcytosine (37) | 24.6 | 6.8 | 1H-NMR | 90–137 | 6 |
| Cytosine (37) | 22.9 | 6.8 | 1H-NMR | 90–137 | 6 |
| Cytosine (this work) | 23.4 | 7.0 | 1H-NMR | 70–180 | 12 |
| 1-Methylcytosine-H+ (this work) | 23.0 | 2.4 | 1H-NMR | 90–200 | 12 |
| Average by 1H-NMR | 23.7 | 1H-NMR | |||
| Other C-N cleavages | |||||
| Acetamide (40) | 23.8 | 6.8 | 1H-NMR | ||
| Ac-gly—gly-NHMe (41) | 22.9 | 6.8 | 1H-NMR |