function  prop = aaratioside(aa) 
%AARATIOSIDE calculates atomic weight ratio of hetero elements in end group to C in side chain.
%
% Author(s) :  Grantham R.
% Reference :  Science 185:862-864(1974).

%   $Revision: 1.1.6.4 $  $Date: 2004/12/24 20:45:56 $
%   Copyright 2003-2004 The MathWorks, Inc.

% no input, return description string 
if nargin == 0, 
  prop = 'AAProp_ Ratio hetero end/side';
  return
end

% create index, and index data 
ndx = double(lower(aa)) - 96;
data = [0.000; ...% A  alanine
        NaN;   ...% B  aspartic acid or asparagine
        2.750; ...% C  cysteine
        1.380; ...% D  aspartic acid
        0.920; ...% E  glutamic acid
        0.000; ...% F  phenylalanine
        0.740; ...% G  glycine
        0.580; ...% H  histidine
        0.000; ...% I  isoleucine
        NaN;   ...% J  not used 
        0.330; ...% K  lysine
        0.000; ...% L  leucine
        0.000; ...% M  methionine
        1.330; ...% N  asparagine
        NaN;   ...% O  not used 
        0.390; ...% P  proline
        0.890; ...% Q  glutamine
        0.650; ...% R  arginine
        1.420; ...% S  serine
        0.710; ...% T  threonine
        NaN;   ...% U  not used 
        0.000; ...% V  valine
        0.130; ...% W  tryptophan
        NaN;   ...% X  any amino acid
        0.200; ...% Y  tyrosine
        NaN;   ...% Z  glutamic acid or glutamine
];

prop = data(ndx);