Table 2. Percentages at 278 K of C3′-Endo Ribose and Anti Glycosidic Angles from NMR and Predicted from 1500 ns of MD Starting with C3′-Endo/Anti Starting Structures.
| % C3′-Endoa | ||||
|---|---|---|---|---|
| residue | NMRb | parm99 | parm99χ_YIL | parm99TOR |
| C1 | 90–100 | 19.5 | 70.3 | 69.4 |
| C2 | 90–100 | 32.0 | 83.6 | 79.3 |
| C3 | 90–100 | 40.8 | 82.5 | 89.7 |
| C4 | 70–80 | 15.3 | 72.2 | 61.9 |
| % Anti | ||||
|---|---|---|---|---|
| residue | NMR | parm99c | parm99χ_YIL | parm99TOR |
| C1 | 90–100 | 51.0 | 99.9 | 100.0 |
| C2 | 90–100 | 93.8 | 100.0 | 100.0 |
| C3 | 90–100 | 99.0 | 100.0 | 100.0 |
| C4 | 90–100 | 94.1 | 99.9 | 99.4 |
a
In MD simulations, ribose was considered C2′-endo or C3′-endo if the pseudorotation phase angle was between 144° and 180° or between 0° and 36°, respectively.
b
C3′-endo ranges were approximated from the H1′–H2′ scalar couplings, assuming that C3′-endo and C2′-endo have scalar couplings of 0 and 10 Hz, respectively.
c
Includes high anti in the percentage. Anti, high anti, and syn are defined as having O4′–C1′–N1–C2 dihedral angles of 180–239°, 240–300°, and 0–120°, respectively.