TABLE 1.
Dependence of G′prompt(ssb), G′total(ssb), and G′total(dsb) on Γ for Films of pUC18 X-irradiated at 4 K
| 1a | 2a | 3a | 4 | 5b | 6c | |
|---|---|---|---|---|---|---|
| G | G′prompt(ssb) (μmol/J) | G′total(ssb)a (μmol/J) | G′total(dsb) (μmol/J) | G′total(ssb)/G′total(dsb) | G′sugar(fr) (μmol/J) | ΔG′ (μmol/J) |
| 2.5 (0.2) | 0.069 (0.014) | 0.092 (0.016) | 0.0052 (0.0008) | 18 (6) | 0.033 (0.005) | 0.06 (0.02) |
| 7.5 (0.6) | 0.058 (0.012) | 0.081 (0.014) | 0.0046 (0.00081) | 17 (4) | 0.040 (0.006) | 0.04 (0.02) |
| 11.5 (0.3) | 0.060 (0.008) | 0.078 (0.008) | 0.0044 (0.0009) | 18 (5) | 0.056 (0.008) | 0.02 (0.02) |
| 15.0 (0.7) | 0.063 (0.008) | 0.077 (0.009) | 0.0047 (0.0008) | 17 (4) | 0.069 (0.010) | 0.01 (0.02) |
| 22.5 (1.1) | 0.054 (0.007) | 0.066 (0.008) | 0.0039 (0.0005) | 17 (3) | 0.079 (0.012) | −0.01 (0.02) |
a
The standard deviations for G′(ssb) and G′(dsb) were calculated from six different sets of gel electrophoresis data and the standard deviations in determining the mass of DNA + solvation shell.
b
G′sugar(fr) is determined from a semiempirical model that predicts 89% of the total free radicals are trapped on the bases and 11% on the sugar–phosphate.17 Unlike the values of Gsugar(fr) in this earlier work, G′sugar(fr) is based on a target mass consisting of DNA + solvation shell; the excess salt is excluded.
c
ΔG′ = G′total(ssb) – G′sugar(fr) = the “shortfall”.