Table 3. Local base-pair step parameters.
| Base-pair step | Minor groove width (Å) | Major groove width (Å) | Slide (Å) | Roll (°) | Tilt (°) | Rise per base (Å) |
|---|---|---|---|---|---|---|
| C2 ≡ G40 | ||||||
| | | | — | — | −0.2 | −1.3 | 1.4 | 3.0 |
| T3 = A39 | ||||||
| | | | — | — | 0.9 | 4.8 | 0.5 | 3.2 |
| G4 ≡ C38 | ||||||
| | | | 12.5 | 18.1 | 0.3 | 3.8 | −2.4 | 3.4 |
| G5 ≡ C37 | ||||||
| | | | 10.9 | 17.3 | −0.4 | 1.9 | −1.7 | 3.5 |
| A6 = T36 | ||||||
| | | | 9.7 | 16.4 | −0.4 | −0.7 | −2.8 | 3.2 |
| A7 = G35 | ||||||
| | | | 9.7 | 17.5 | −0.6 | −3.7 | 0.9 | 3.4 |
| mC8 = T34 | ||||||
| | | | 11.2 | 18.9 | 0.3 | 2.3 | 1.8 | 3.4 |
| G9 ≡ mC33 | ||||||
| | | | 12.3 | 17.9 | 0.5 | 3.3 | 0.1 | 3.1 |
| G10 ≡ C32 | ||||||
| | | | 11.6 | 16.5 | 1.1 | 1.7 | −3.5 | 3.3 |
| A11 = T31 | ||||||
| | | | 9.9 | 18.8 | 0.0 | −2.0 | 1.8 | 3.3 |
| A12 = T30 | ||||||
| | | | 8.7 | 17.4 | −0.6 | 0.2 | −1.9 | 3.2 |
| T13 = A29 | ||||||
| | | | 9.0 | 20.0 | −0.5 | −2.9 | 0.6 | 3.2 |
| T14 = A28 | ||||||
| | | | 9.3 | 19.8 | −0.5 | −1.0 | −1.2 | 3.5 |
| C15 ≡ G27 | ||||||
| | | | 9.6 | 17.2 | 0.1 | −1.7 | 1.3 | 3.1 |
| T16 = A26 | ||||||
| | | | 10.3 | 18.1 | 0.3 | −2.7 | −1.5 | 3.3 |
| T17 = A25 | ||||||
| | | | 10.2 | 16.8 | 1.2 | −2.1 | 0.4 | 3.4 |
| C18 ≡ G24 | ||||||
| | | | — | — | 0.7 | −3.0 | 0.0 | 3.3 |
| T19 = A23 | ||||||
| | | | — | — | 1.6 | −1.3 | 3.3 | 3.4 |
| A20 = T22 | ||||||
| Average | 10.4 | 17.9 | 0.2 | −0.2 | −0.2 | 3.3 |
The minor and major groove widths were measured considering the directions of the sugar-phosphate backbones. A useful measurement of the inter-phosphate distance across the major opening is obtained by subtracting 5.8 Å of the van der Waals radii of two phosphate groups from the calculated values. “=” and “≡” represent the conventional Watson-Crick hydrogen bonds between adenine-thymine and cytosine:guanine base-pairs, respectively.