Table 2.
Average valence and multipole populations for the atoms of the polypeptide main chain
| Atom | Local O-x axis ∖y | Valence population | Dipoles | Quadruples | Octupoles | ||
|---|---|---|---|---|---|---|---|
| Cα | Cα-C | Pval | Oxz2 | Oyz2 | Ox3 | Oz3 | |
| ∖N | 4.04 (7) | −0.177 (16) | −0.276 (25) | 0.269 (32) | 0.069 (12) | ||
| 3.96 (4) | −0.092 (11) | −0.246 (11) | 0.184 (10) | 0.049 (10) | |||
| C | C-O | Dx | Qz2 | Qx2-y2 | Ox3 | ||
| ∖N | 3.98 (4) | 0.106 (10) | −0.308 (15) | 0.107 (14) | 0.424 (19) | ||
| 4.32 (4) | 0.068 (9) | −0.268 (11) | 0.093 (10) | 0.342 (11) | |||
| O | O-C | Dx | Qz2 | Qx2-y2 | |||
| ∖N | 6.29 (2) | −0.076 (10) | −0.074 (7) | −0.073(7) | |||
| 5.96 (3) | Fixed | Fixed | Fixed | ||||
| N | N-C | Dy | Qz2 | Ox3 | |||
| ∖Cα | 5.31 (3) | −0.077 (12) | −0.0522 (13) | 0.271 (9) | |||
| 4.95 (4) | −0.011 (10) | 0.030 (10) | 0.150 (8) | ||||
| HN | HN-N | Dx | |||||
| ∖C | 0.61 (3) | 0.177 (16) | |||||
| 0.88 (2) | 0.229 (12) | ||||||
| Hα | Hα-Cα | Dx | |||||
| ∖N | 0.77 (2) | 0.151 (11) | |||||
| 0.89 (2) | 0.194 (11) | ||||||
The upper value is the average charge density parameter in the database, with the SD in the sample given in parenthesis. The lower value and its uncertainty is obtained from the crambin multipole refinement. In the local axis system of an atom, the Ox direction is defined by the first two atoms, and the Oxy plane is defined by the third atom.