Hello Neha;
I am appending some informations regarding you query about interaction 
energy calculation.
Neha Gandhi wrote:
>Can I also use a single trajectory method in such case?
>  
>
You can use single trajectory approach to compare the ligand affinity 
against one receptor, however, if you would like to include the ligand 
induced energy ( free energy of adaptation) which would be the 
difference in the free energy between the holo and apo state of the 
molecule, than you should use three separate trajectory approach.
deltaG(adopt) = < Gmmpbsa(holo) > - < Gmmpbsa(apo) >
The paper by Masukawa, et. al. /J. Med. Chem.,/ *46* (26), 5628 -5637, 
2003. and /J. Am. Chem. Soc.,/ *128* (39), 12766 -12777, 2006. discused 
it in detail.
>On Mon, Jun 9, 2008 at 1:49 PM, Neha Gandhi <n.gandhiau.gmail.com> wrote:
>  
>
>>Dear Amber users,
>>
>>Can anybody tell me if I should use the final snapshots of the ligand,
>>receptor and complex to run the final MM-PBSA script along with
>>delphi? There is a conformational change in the complex.
>>
>>    
>>
As you know the sampling issue is one of the key point for accurate 
binding energy calculation. So, the only one snapshot would not give you 
the overall averaged interaction energy, however, in vivo experiment 
overall conformational energy is measured. Thats why we use all the 
conformations which sampled during the dynamics, and then we averaged it 
to get <deltaE>. I would prefer to include all the conformations with a 
frequency of 10 or 20 ps, I would leave the part of trajectory which is 
not fully equillibriated.
with regards,
Navnit
>>--
>>Regards,
>>Neha Gandhi,
>>School of Biomedical Sciences,
>>Curtin University of Technology,
>>GPO Box U1987 Perth,
>>Western Australia 6845
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>>    
>>
>
>
>
>  
>
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Received on Wed Jun 11 2008 - 06:07:22 PDT