Single-letter side-chain codes
==============================

This is a list of extended single-letter amino-acid sidechain codes recognized by `pmlbeta`

+--------+-------------------------------------+
| Letter | Side-chain                          |
+========+=====================================+
|   A    | alanine                             |
+--------+-------------------------------------+
|   C    | cysteine (neutral)                  |
+--------+-------------------------------------+
|   CM   | cysteine (anionic)                  |
+--------+-------------------------------------+
|   D    | aspartate (ionic)                   |
+--------+-------------------------------------+
|   DH   | aspartic acid (protonated)          |
+--------+-------------------------------------+
|   E    | glutamate (ionic)                   |
+--------+-------------------------------------+
|   EH   | glutamic acid (protonated)          |
+--------+-------------------------------------+
|   G    | glycine (i.e. no side-chain)        |
+--------+-------------------------------------+
|   HD   | histidine protonated on Nδ          |
+--------+-------------------------------------+
|   HE   | histidine protonated on Nε          |
+--------+-------------------------------------+
|   HH   | doubly protonated histidine         |
+--------+-------------------------------------+
|   H    | unprotonated histidine              |
+--------+-------------------------------------+
|   I    | isoleucine                          |
+--------+-------------------------------------+
|   K    | lysine (charged)                    |
+--------+-------------------------------------+
|   KN   | lysine (neutral)                    |
+--------+-------------------------------------+
|   L    | leucine                             |
+--------+-------------------------------------+
|   M    | methionine                          |
+--------+-------------------------------------+
|   N    | asparagine                          |
+--------+-------------------------------------+
|   O    | ornithine (charged)                 |
+--------+-------------------------------------+
|   ON   | ornithine (neutral)                 |
+--------+-------------------------------------+
|   P    | proline (only alpha-amino acid)     |
+--------+-------------------------------------+
|   Q    | glutamine                           |
+--------+-------------------------------------+
|   R    | arginine                            |
+--------+-------------------------------------+
|   S    | serine                              |
+--------+-------------------------------------+
|   T    | threonine                           |
+--------+-------------------------------------+
|   V    | valine                              |
+--------+-------------------------------------+
|   W    | tryptophan                          |
+--------+-------------------------------------+
|   Y    | tyrosine                            |
+--------+-------------------------------------+