Dear Sir/Madam,
 
I have done a caloritm measurement on a binding between two proteins, and a protein with DNA.  
 
Experimentally, they are in the found to be -10 and -16 kcal/mol, respectively.
 
I also do the MM-GBSA binding energies for the pairs of data, however, they were found to be -61 and -120 kcal/mol.
 
Is it well know that MM-GBSA tends to overestimate the binding energies?  Can I rationizal the enhanced binding energies or give reasons why they are different so large?  
 
I thought it could be due to salt was added in the experiment, ~ 0.2M NaCl.  So, I add salt concentrate to ~ 0.2M.  However, the theoretically energy only down to -50 and -100 kcal/mol, still far away from the experimental results.  Any suggestions on the source of error?
 
Best regards,
 
Catherine 		 	   		  
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Received on Mon Feb 21 2011 - 03:00:04 PST