function  prop = aaalpha_helixfasman(aa) 
%AAALPHA_HELIXFASMAN calculates the conformational parameter for alpha helix.
%
%   AAALPHA_HELIXFASMAN(AA) calculates the conformational parameter for
%   alpha helix (computed from 29 proteins). 
%
% Author(s) :  Chou P.Y., Fasman G.D.
% Reference :  Adv. Enzym. 47:45-148(1978).

%   $Revision: 1.1.6.4 $  $Date: 2004/12/24 20:45:09 $
%   Copyright 2003-2004 The MathWorks, Inc.

% no input, return description string 
if nargin == 0, 
  prop = 'AAProp_ Alpha helix (Chou & Fasman)';
  return
end

% create index, and index data 
ndx = double(lower(aa)) - 96;
data = [1.420; ...% A  alanine
        NaN;   ...% B  aspartic acid or asparagine
        0.700; ...% C  cysteine
        1.010; ...% D  aspartic acid
        1.510; ...% E  glutamic acid
        1.130; ...% F  phenylalanine
        0.570; ...% G  glycine
        1.000; ...% H  histidine
        1.080; ...% I  isoleucine
        NaN;   ...% J  not used 
        1.160; ...% K  lysine
        1.210; ...% L  leucine
        1.450; ...% M  methionine
        0.670; ...% N  asparagine
        NaN;   ...% O  not used 
        0.570; ...% P  proline
        1.110; ...% Q  glutamine
        0.980; ...% R  arginine
        0.770; ...% S  serine
        0.830; ...% T  threonine
        NaN;   ...% U  not used 
        1.060; ...% V  valine
        1.080; ...% W  tryptophan
        NaN;   ...% X  any amino acid
        0.690; ...% Y  tyrosine
        NaN;   ...% Z  glutamic acid or glutamine
];

prop = data(ndx);
