Amino acids
The 20 standard amino acids that make up peptides: codes, masses, side-chain chemistry and the stability issues each one brings.
| Amino acid | 3-letter | 1-letter | Side chain | Residue mass (mono, Da) | Hydropathy |
|---|---|---|---|---|---|
| Alanine | Ala | A | A Hydrophobic | 71.0371 | +1.8 |
| Arginine | Arg | R | R Basic | 156.1011 | -4.5 |
| Asparagine | Asn | N | N Polar | 114.0429 | -3.5 |
| Aspartic acid | Asp | D | D Acidic | 115.0269 | -3.5 |
| Cysteine | Cys | C | C Special (Gly, Pro, Cys) | 103.0092 | +2.5 |
| Glutamic acid | Glu | E | E Acidic | 129.0426 | -3.5 |
| Glutamine | Gln | Q | Q Polar | 128.0586 | -3.5 |
| Glycine | Gly | G | G Special (Gly, Pro, Cys) | 57.0215 | -0.4 |
| Histidine | His | H | H Basic | 137.0589 | -3.2 |
| Isoleucine | Ile | I | I Hydrophobic | 113.0841 | +4.5 |
| Leucine | Leu | L | L Hydrophobic | 113.0841 | +3.8 |
| Lysine | Lys | K | K Basic | 128.0950 | -3.9 |
| Methionine | Met | M | M Hydrophobic | 131.0405 | +1.9 |
| Phenylalanine | Phe | F | F Hydrophobic | 147.0684 | +2.8 |
| Proline | Pro | P | P Special (Gly, Pro, Cys) | 97.0528 | -1.6 |
| Serine | Ser | S | S Polar | 87.0320 | -0.8 |
| Threonine | Thr | T | T Polar | 101.0477 | -0.7 |
| Tryptophan | Trp | W | W Hydrophobic | 186.0793 | -0.9 |
| Tyrosine | Tyr | Y | Y Hydrophobic | 163.0633 | -1.3 |
| Valine | Val | V | V Hydrophobic | 99.0684 | +4.2 |
For non-standard residues such as Aib, norleucine and pyroglutamate, see the amino acid reference guide.