Table 1.
Formation of Cl2•− and sugar radicals via photoexcitation of one-electron oxidized guanine in DNA systems by 405 and 640 nm at 143 K and at different pHs a
| Compound | λ (nm) |
pH | Percent convertedb (Time (h)) |
Radicals produced (%) | |||
|---|---|---|---|---|---|---|---|
| Cl2•− | C1′• | C3′• | C5′• | ||||
| dGuo | 405 | 3 | 90 (1h) | 15 | - | 25 | 50 |
| 5 | 90 (1h) | 10 | - | 35 | 45 | ||
| 9 | 20 (0.5) | - | - | 5 | 15 | ||
| 640 | 3 | 75 (3.5) | - | 15 | 30 | 30 | |
| 5 | 80 (5.5) | - | 15 | 35 | 30 | ||
| 9 | - (0.5) | - | - | - | - | ||
| TGT | 405 | 3 | 70 (0.5) | 30 | 35 | - | 5 |
| 5 | 70 (0.5) | 30 | 35 | - | 5 | ||
| 9 | - | - | - | - | - | ||
| 640 | 3 | 30 (3) | - | 30 | - | - | |
| 5 | 30 (5) | - | 30 | - | - | ||
| d[TGCGCGCA]2 | 405 | 3 | 85 (0.5) | 60 | 20 | - | 5 |
| 5 | 85 (0.5) | 30 | 50 | - | 5 | ||
| 9 | - (0.5) | - | - | - | - | ||
| 640 | 3 | 15 (1h) | - | 15 | - | - | |
| 5 | ca. 5 (1h) | - | ca. 5 | - | - | ||
| d[TATAGCGGCCTATA]2 | 405 | 3 | 60 (0.5) | 30 | 25 | - | 5 |
| 5 | 60 (0.5) | 20 | 35 | - | 5 | ||
| 9 | - (0.5) | - | - | - | - | ||
| 640 | 3 | 10 (0.5) | - | 10 | - | - | |
| 5 | ca.5 (0.5) | - | ca.5 | - | - | ||
a
Radical percentages are ±10% relative error 14a
b
Percentage conversion of one-electron oxidized G to various sugar radicals and Cl2•−. The total spectral intensities before and after photoexcitation were found to be nearly identical.