Relative accessible surface area

Relative accessible surface area or relative accessibility of a protein residue is a measure of residue solvent exposure. It can be calculated by formula:

$RelAcc = 100 * Acc / MaxAcc$ ^[1]

where $Acc$ is the solvent accessible surface area and $MaxAcc$ is the maximum possible solvent accessible surface area for the residue in ${\AA}^2$.

Maximum possible solvent accessible surface area for each Amino acid can be taken from the table below

^[2]

Amino acid code	Maximum solvent accessible surface
A	106
B	160
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
Y	222
Z	196

where B stands for D or N; Z for E or Q and X for an undetermined Amino acid.

References

1. Hyunsoo, Kim; Haesun, Park. "Prediction of Protein Relative Solvent Accessibility with Support Vector Machines and Long-range Interaction 3D Local Descriptor" (PDF). Retrieved 10 April 2015.
2. Rost, Burkhard; Sander, Chris (November 1994). "Conservation and Prediction of Solvent Accessibility in Protein Families". Proteins 20 (Conservation and Prediction of Solvent Accessibility in Protein Families): 218. doi:10.1002/prot.340200303. PMID 7892171. Retrieved 10 April 2015.