Amino acids are building blocks of proteins.
Here are the 20 most common amino acids.
| Name | Three letter code | One letter code | Molecular Weight | Molecular Formula | Residue Formula | Residue Weight (-H2O) | pKa | pKb | pKx | pl |
|---|---|---|---|---|---|---|---|---|---|---|
| Alanine | Ala | A | 89.10 | C3H7NO2 | C3H5NO | 71.08 | 2.34 | 9.69 | – | 6.00 |
| Arginine | Arg | R | 174.20 | C6H14N4O2 | C6H12N4O | 156.19 | 2.17 | 9.04 | 12.48 | 10.76 |
| Asparagine | Asn | N | 132.12 | C4H8N2O3 | C4H6N2O2 | 114.11 | 2.02 | 8.80 | – | 5.41 |
| Aspartic acid | Asp | D | 133.11 | C4H7NO4 | C4H5NO3 | 115.09 | 1.88 | 9.60 | 3.65 | 2.77 |
| Cysteine | Cys | C | 121.16 | C3H7NO2S | C3H5NOS | 103.15 | 1.96 | 10.28 | 8.18 | 5.07 |
| Glutamic acid | Glu | E | 147.13 | C5H9NO4 | C5H7NO3 | 129.12 | 2.19 | 9.67 | 4.25 | 3.22 |
| Glutamine | Gln | Q | 146.15 | C5H10N2O3 | C5H8N2O2 | 128.13 | 2.17 | 9.13 | – | 5.65 |
| Glycine | Gly | G | 75.07 | C2H5NO2 | C2H3NO | 57.05 | 2.34 | 9.60 | – | 5.97 |
| Histidine | His | H | 155.16 | C6H9N3O2 | C6H7N3O | 137.14 | 1.82 | 9.17 | 6.00 | 7.59 |
| Hydroxyproline | Hyp | O | 131.13 | C5H9NO3 | C5H7NO2 | 113.11 | 1.82 | 9.65 | – | – |
| Isoleucine | Ile | I | 131.18 | C6H13NO2 | C6H11NO | 113.16 | 2.36 | 9.60 | – | 6.02 |
| Leucine | Leu | L | 131.18 | C6H13NO2 | C6H11NO | 113.16 | 2.36 | 9.60 | – | 5.98 |
| Lysine | Lys | K | 146.19 | C6H14N2O2 | C6H12N2O | 128.18 | 2.18 | 8.95 | 10.53 | 9.74 |
| Methionine | Met | M | 149.21 | C5H11NO2S | C5H9NOS | 131.20 | 2.28 | 9.21 | – | 5.74 |
| Phenylalanine | Phe | F | 165.19 | C9H11NO2 | C9H9NO | 147.18 | 1.83 | 9.13 | – | 5.48 |
| Proline | Pro | P | 115.13 | C5H9NO2 | C5H7NO | 97.12 | 1.99 | 10.60 | – | 6.30 |
| Pyroglutamatic | Glp | U | 139.11 | C5H7NO3 | C5H5NO2 | 121.09 | – | – | – | 5.68 |
| Serine | Ser | S | 105.09 | C3H7NO3 | C3H5NO2 | 87.08 | 2.21 | 9.15 | – | 5.68 |
| Threonine | Thr | T | 119.12 | C4H9NO3 | C4H7NO2 | 101.11 | 2.09 | 9.10 | – | 5.60 |
| Tryptophan | Trp | W | 204.23 | C11H12N2O2 | C11H10N2O | 186.22 | 2.83 | 9.39 | – | 5.89 |
| Tyrosine | Tyr | Y | 181.19 | C9H11NO3 | C9H9NO2 | 163.18 | 2.20 | 9.11 | 10.07 | 5.66 |
| Valine | Val | V | 117.15 | C5H11NO2 | C5H9NO | 99.13 | 2.32 | 9.62 | – | 5.96 |