Calculating residue-by-residue binding energies

 Dear Netters,
 I want to calculate the binding energy of a protein on a surface of glass. I
 have a model glass surface constructed, and the protein-glass binding energy
 is pretty straightforward to calculate.  However, I want to calculate
 (estimate) the binding energy of the protein to glass on a residue-by-residue
 basis.  In other words, I want to identify energetically which residues are
 functionally most important for the binding affinity of the protein to the
 Any suggestions are much appreciated.  From recent conversations, I gather that
 interest in this question is widespread.  So I will post a summary of responses
 if I receive several hits.
 thanks much ...
 Bill Welsh
 Dept. of Chemistry
 Univ. of Missouri-St. Louis