Table 1.
Distribution and strain energies of 42,690 disulfides in X-ray structures.
| Designation | Number | Incidence, % | DSE, kJ.mol-1 | Cα-Cα', Å |
| -LHSpiral | 12684 | 29.71 | 10.5 (10.4–10.6) | 5.77 (5.76–5.78) |
| -RHHook | 4344 | 10.18 | 13.3 (13.1–13.6) | 5.26 (5.22–5.30) |
| -RHStaple | 3641 | 8.53 | 17.7 (17.5–17.9) | 4.18 (4.17–4.19) |
| +/-LHSpiral | 3563 | 8.35 | 13.2 (12.9–13.4) | 6.11 (6.09–6.12) |
| -/+RHHook | 2445 | 5.73 | 11.3 (11.0–11.5) | 5.09 (5.07–5.10) |
| +/-RHSpiral | 2392 | 5.60 | 13.6 (13.3–13.9) | 6.16 (6.06–6.26) |
| -RHSpiral | 2311 | 5.41 | 11.9 (11.6–12.3) | 5.75 (5.71–5.78) |
| -LHHook | 2262 | 5.30 | 14.6 (14.2–15.0) | 5.65 (5.62–5.68) |
| +/-RHHook | 2051 | 4.80 | 14.1 (13.7–14.5) | 5.39 (5.28–5.49) |
| -/+LHHook | 1949 | 4.57 | 12.9 (12.5–13.3) | 5.96 (5.92–5.99) |
| +RHSpiral | 1599 | 3.75 | 15.7 (15.4–15.9) | 6.43 (6.41–6.44) |
| +/-LHHook | 763 | 1.79 | 17.1 (16.3–17.9) | 5.47 (5.42–5.52) |
| +/-LHStaple | 618 | 1.45 | 15.3 (14.3–16.2) | 5.18 (5.09–5.27) |
| -LHStaple | 599 | 1.40 | 14.9 (13.8–16.0) | 5.80 (5.70–5.89) |
| +LHHook | 451 | 1.06 | 17.2 (16.2–18.2) | 5.87 (5.81–5.94) |
| +/-RHStaple | 301 | 0.71 | 19.0 (17.9–20.2) | 5.11 (5.03–5.19) |
| +LHSpiral | 293 | 0.69 | 18.2 (16.9–19.5) | 6.35 (6.30–6.40) |
| +RHHook | 269 | 0.63 | 20.8 (19.4–22.2) | 5.91 (5.83–5.99) |
| +LHStaple | 109 | 0.26 | 12.2 (9.7–14.6) | 5.66 (5.54–5.77) |
| +RHStaple | 46 | 0.11 | 33.0 (29.3–36.7) | 5.94 (5.63–6.26) |
| all disulfides | 42690 | 13.1 (13.1–13.2) | 5.59 (5.58–5.60) |
The disulfide bonds were separated into twenty configurations based on the sign of χ1, χ2, χ3, χ2' and χ1' angles [8]. The dihedral strain energy (DSE) and distance between the two α carbon atoms were calculated for each disulfide and the mean and 95% confidence intervals is shown for each group.