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Amino Acid Codes.
one- and three-letter reference for the 20 standard residues.
| Amino acid | 3-letter | 1-letter | Side chain | MW (Da) |
|---|---|---|---|---|
| Alanine | Ala | A | Nonpolar | 89.09 |
| Arginine | Arg | R | Basic | 174.20 |
| Asparagine | Asn | N | Polar | 132.12 |
| Aspartate | Asp | D | Acidic | 133.10 |
| Cysteine | Cys | C | Polar · thiol | 121.16 |
| Glutamate | Glu | E | Acidic | 147.13 |
| Glutamine | Gln | Q | Polar | 146.15 |
| Glycine | Gly | G | Nonpolar | 75.07 |
| Histidine | His | H | Basic | 155.16 |
| Isoleucine | Ile | I | Nonpolar | 131.17 |
| Leucine | Leu | L | Nonpolar | 131.17 |
| Lysine | Lys | K | Basic | 146.19 |
| Methionine | Met | M | Nonpolar · sulfur | 149.21 |
| Phenylalanine | Phe | F | Aromatic | 165.19 |
| Proline | Pro | P | Nonpolar · cyclic | 115.13 |
| Serine | Ser | S | Polar | 105.09 |
| Threonine | Thr | T | Polar | 119.12 |
| Tryptophan | Trp | W | Aromatic | 204.23 |
| Tyrosine | Tyr | Y | Aromatic · polar | 181.19 |
| Valine | Val | V | Nonpolar | 117.15 |
Molecular weights are for the free amino acid. For peptide-bond MW use residue mass (subtract 18.02 Da per bond). Sequence convention is N-terminus to C-terminus, e.g. Gly-Glu-Pro-Pro-Pro.
