chi_angles_atoms
============================

氨基酸中决定侧链扭转角的原子基团的名称，每个氨基酸最多有四个侧链扭转角，其中ALA与GLY没有侧链扭转角；每个扭转角由4个原子基团的位置决定（二面角）。

+------+-----------------------------------------------------------------------------------------------------------+
| key  | value                                                                                                     |
+======+===========================================================================================================+
| ALA  | []                                                                                                        |
+------+-----------------------------------------------------------------------------------------------------------+
| ARG  | [['N', 'CA', 'CB', 'CG'], ['CA', 'CB', 'CG', 'CD'], ['CB', 'CG', 'CD', 'NE'], ['CG', 'CD', 'NE', 'CZ']]   |
+------+-----------------------------------------------------------------------------------------------------------+
| ASN  | [['N', 'CA', 'CB', 'CG'], ['CA', 'CB', 'CG', 'OD1']]                                                      |
+------+-----------------------------------------------------------------------------------------------------------+
| ASP  | [['N', 'CA', 'CB', 'CG'], ['CA', 'CB', 'CG', 'OD1']]                                                      |
+------+-----------------------------------------------------------------------------------------------------------+
| CYS  | [['N', 'CA', 'CB', 'SG']]                                                                                 |
+------+-----------------------------------------------------------------------------------------------------------+
| GLN  | [['N', 'CA', 'CB', 'CG'], ['CA', 'CB', 'CG', 'CD'], ['CB', 'CG', 'CD', 'OE1']]                            |
+------+-----------------------------------------------------------------------------------------------------------+
| GLU  | [['N', 'CA', 'CB', 'CG'], ['CA', 'CB', 'CG', 'CD'], ['CB', 'CG', 'CD', 'OE1']]                            |
+------+-----------------------------------------------------------------------------------------------------------+
| GLY  | []                                                                                                        |
+------+-----------------------------------------------------------------------------------------------------------+
| HIS  | [['N', 'CA', 'CB', 'CG'], ['CA', 'CB', 'CG', 'ND1']]                                                      |
+------+-----------------------------------------------------------------------------------------------------------+
| ILE  | [['N', 'CA', 'CB', 'CG1'], ['CA', 'CB', 'CG1', 'CD1']]                                                    |
+------+-----------------------------------------------------------------------------------------------------------+
| LEU  | [['N', 'CA', 'CB', 'CG'], ['CA', 'CB', 'CG', 'CD1']]                                                      |
+------+-----------------------------------------------------------------------------------------------------------+
| LYS  | [['N', 'CA', 'CB', 'CG'], ['CA', 'CB', 'CG', 'CD'], ['CB', 'CG', 'CD', 'CE'], ['CG', 'CD', 'CE', 'NZ']]   |
+------+-----------------------------------------------------------------------------------------------------------+
| MET  | [['N', 'CA', 'CB', 'CG'], ['CA', 'CB', 'CG', 'SD'], ['CB', 'CG', 'SD', 'CE']]                             |
+------+-----------------------------------------------------------------------------------------------------------+
| PHE  | [['N', 'CA', 'CB', 'CG'], ['CA', 'CB', 'CG', 'CD1']]                                                      |
+------+-----------------------------------------------------------------------------------------------------------+
| PRO  | [['N', 'CA', 'CB', 'CG'], ['CA', 'CB', 'CG', 'CD']]                                                       |
+------+-----------------------------------------------------------------------------------------------------------+
| SER  | [['N', 'CA', 'CB', 'OG']]                                                                                 |
+------+-----------------------------------------------------------------------------------------------------------+
| THR  | [['N', 'CA', 'CB', 'OG1']]                                                                                |
+------+-----------------------------------------------------------------------------------------------------------+
| TRP  | [['N', 'CA', 'CB', 'CG'], ['CA', 'CB', 'CG', 'CD1']]                                                      |
+------+-----------------------------------------------------------------------------------------------------------+
| TYR  | [['N', 'CA', 'CB', 'CG'], ['CA', 'CB', 'CG', 'CD1']]                                                      |
+------+-----------------------------------------------------------------------------------------------------------+
| VAL  | [['N', 'CA', 'CB', 'CG1']]                                                                                |
+------+-----------------------------------------------------------------------------------------------------------+