The following table contains a list of the amino acid 1 and 3 letter codes.
| Amino Acid | 3-Letter | 1-Letter | Residue mass (A0, Da) |
|---|---|---|---|
| Alanine | Ala | A | 71.037114 |
| Arginine | Arg | R | 156.101111 |
| Asparagine | Asn | N | 114.042927 |
| Aspartic acid | Asp | D | 115.026943 |
| Cysteine | Cys | C | 103.009185 |
| Glutamic acid | Glu | E | 129.042593 |
| Glutamine | Gln | Q | 128.058578 |
| Glycine | Gly | G | 57.021464 |
| Histidine | His | H | 137.058912 |
| Isoleucine | Ile | I | 113.084064 |
| Leucine | Leu | L | 113.084064 |
| Lysine | Lys | K | 128.094963 |
| Methionine | Met | M | 131.040485 |
| Phenylalanine | Phe | F | 147.068414 |
| Proline | Pro | P | 97.052764 |
| Serine | Ser | S | 87.032028 |
| Threonine | Thr | T | 101.047679 |
| Tryptophan | Trp | W | 186.079313 |
| Tyrosine | Tyr | Y | 163.06332 |
| Valine | Val | V | 99.068414 |
Additional codes for amino acids coded by unusual translations:
| Amino acid | 3-Letter | 1-Letter | Residue mass (A0, Da) |
|---|---|---|---|
| Selenocysteine | Sec | U | 150.95363 |
| Pyrrolysine | Pyl | O | 237.147727 |
| stop | n/a | * | n/a |
Additional codes for ambiguous residues in protein sequences:
| Ambiguous Amino Acids | 3-Letter | 1-Letter | X! translation |
|---|---|---|---|
| Asparagine or aspartic acid | Asx | B | D |
| Glutamine or glutamic acid | Glx | Z | E |
| Leucine or Isoleucine | Xle | J | L |
| Unspecified or unknown amino acid | Xaa | X | * |