TABLE 2.
pK values of the 20 biological amino acids, including those of the side chains of seven titratable residues
| Amino Acid | α-carboxylic acid | α-amino | Side chain |
|---|---|---|---|
| Alanine | 2.35 | 9.87 | |
| Arginine | 2.01 | 9.04 | 12.48 |
| Asparagine | 2.02 | 8.80 | |
| Aspartic Acid | 2.10 | 9.82 | 3.86 |
| Cysteine | 2.05 | 10.25 | 8.00 |
| Glutamic Acid | 2.10 | 9.47 | 4.07 |
| Glutamine | 2.17 | 9.13 | |
| Glycine | 2.35 | 9.78 | |
| Histidine | 1.77 | 9.18 | 6.10 |
| Isoleucine | 2.32 | 9.76 | |
| Leucine | 2.33 | 9.74 | |
| Lysine | 2.18 | 8.95 | 10.53 |
| Methionine | 2.28 | 9.21 | |
| Phenylalanine | 2.58 | 9.24 | |
| Proline | 2.00 | 10.60 | |
| Serine | 2.21 | 9.15 | |
| Threonine | 2.09 | 9.10 | |
| Tryptophan | 2.38 | 9.39 | |
| Tyrosine | 2.20 | 9.11 | 10.07 |
| Valine | 2.29 | 9.72 |