The following quotient is used to convert residue solvent accessibility into relative accessbility:
solvent accessibility in square Angstrom relative accessibility = ---------------------------------------- maximal accessibility
with the following values (in square Angstrom) for the amino acids:
+-------------+-------------+
| amino acid | maximal acc | note:
+-------------+-------------+
| A | 106 |
| B | 157 | # D or N
| C | 135 |
| D | 163 |
| E | 194 |
| F | 197 |
| G | 84 |
| H | 184 |
| I | 169 |
| K | 205 |
| L | 164 |
| M | 188 |
| N | 157 |
| P | 136 |
| Q | 198 |
| R | 248 |
| S | 130 |
| T | 142 |
| V | 142 |
| W | 227 |
| X | 180 | # undetermined (deliberate)
| Y | 222 |
| Z | 194 | # E or Q
+-------------+-------------+
The following cut-off thresholds are used for projecting relative solvent accessibility onto two states:
+-------------+----------------------------+
| state | relative accessibility |
+-------------+----------------------------+
| buried | 0% - 14% |
| exposed | 15% - 100% |
+-------------+----------------------------+