Torsion Angle Defintions
The torsion angle definitions listed below are identical to those given in Lovell, S.C., et. al. "The Penultimate Rotamer Library." Proteins 40:389-408. They are standard in the protein nomenclature.
Backbone Angle Defintions
| Torsion | Atom #1 | Atom #2 | Atom #3 | Atom #4 |
| φ | Ci-1 | Ni | CAi | Ci |
| ψ | Ni | CAi | Ci | Ni+1 |
| ω | CAi-1 | Ci-1 | Ni | CAi |
χ1 Angle Defintions
| Amino Acid | Atom #1 | Atom #2 | Atom #3 | Atom #4 |
| ARG | N | CA | CB | CG |
| ASN | N | CA | CB | CG |
| ASP | N | CA | CB | CG |
| CYS | N | CA | CB | SG |
| SER | N | CA | CB | OG |
| GLN | N | CA | CB | CG |
| GLU | N | CA | CB | CG |
| HIS | N | CA | CB | CG |
| ILE | N | CA | CB | CG1 |
| LEU | N | CA | CB | CG |
| LYS | N | CA | CB | CG |
| MET | N | CA | CB | CG |
| PHE | N | CA | CB | CG |
| PRO | N | CA | CB | CG |
| THR | N | CA | CB | OG1 |
| TRP | N | CA | CB | CG |
| TYR | N | CA | CB | CG |
| VAL | N | CA | CB | CG1 |
| GLX | N | CA | CB | CG |
| ASX | N | CA | CB | CG |
| CYX | N | CA | CB | CG |
| PCA | N | CA | CB | CG |
χ2 Angle Defintions
| Amino Acid | Atom #1 | Atom #2 | Atom #3 | Atom #4 |
| ARG | CA | CB | CG | CD |
| ASN | CA | CB | CG | OD1 |
| ASP | CA | CB | CG | OD1 |
| ASX | CA | CB | CG | OD1 |
| GLN | CA | CB | CG | CD |
| GLU | CA | CB | CG | CD |
| GLX | CA | CB | CG | CD |
| HIS | CA | CB | CG | ND1 |
| ILE | CA | CB | CG1 | CD1 |
| LEU | CA | CB | CG | CD1 |
| LYS | CA | CB | CG | CD |
| MET | CA | CB | CG | SD |
| PHE | CA | CB | CG | CD1 |
| PRO | CA | CB | CG | CD |
| TRP | CA | CB | CG | CD1 |
| TYR | CA | CB | CG | CD1 |
χ3 Angle Defintions
| Amino Acid | Atom #1 | Atom #2 | Atom #3 | Atom #4 |
| ARG | CB | CG | CD | NE |
| GLN | CB | CG | CD | OE1 |
| GLU | CB | CG | CD | OE1 |
| GLX | CB | CG | CD | OE1 |
| LYS | CB | CG | CD | CE |
| MET | CB | CG | SD | CE |
χ4 Angle Defintions
| Amino Acid | Atom #1 | Atom #2 | Atom #3 | Atom #4 |
| ARG | CG | CD | NE | CZ |
| LYS | CG | CD | CE | NZ |
