Normalisation of solvent accessibility

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%              |
    +-------------+----------------------------+