Table: pKa values of ionizable side chains in a series of protein
| Group | Content % | Buried % | pKaint in AAXAA | pKa avg | low pKa | high pKa | # measurments |
| Asp | 5.2 | 56 | 3.9 | 3.5 + 1.2 | 0.5 | 9.2 | 139 |
| Glu | 6.5 | 48 | 4.3 | 4.2 + 0.9 | 2.1 | 8.8 | 153 |
| His | 2.2 | 72 | 6.5 | 6.6 + 1.0 | 2.4 | 9.2 | 131 |
| Cys | 1.2 | 90 | 8.6 | 6.8 + 2.7 | 2.5 | 11.1 | 25 |
| Tyr | 3.2 | 67 | 9.8 | 10.3 + 1.2 | 6.1 | 12.1 | 20 |
| Lys | 5.9 | 34 | 10.4 | 10.5 + 1.1 | 5.7 | 12.1 | 35 |
| Arg | 5.1 | 56 | 12.3 | ||||
| C term | 3.7 | 3.3 + 0.8 | 2.4 | 5.9 | 22 | ||
| N term | 8.0 | 7.7 + 0.5 | 6.8 | 9.1 | 16 |