Subject: CoMFA with racemic compunds?

From: Stefan Schmitt <schmitt@wocx04>
Date: Mon, 10 Feb 1997 11:06:46 +0100 (MET)

Dear Computer Chemists,
stereo
 I am doing 3D-QSAR analysis using SYBYL's standard QSAR module from 
Tripos. 
The compounds I am analyzing contain one (and for some derivatives two) 
stereogenic center(s). Biological data (IC50) however, is due to 
experimental reasons only availible for racemic mixtures (or diastereomeric 
mixtures in the case of two stereogenic centers).  

My question is now, how to handle this information for a CoMFAnalysis:
Is it right to use both isomeric structures as CoMFA-input and give them the 
same activity? 
It may sound logical but I am not aware if such a proceeding would 
falsify the input for the PLS-analysis.
Alternatively you could use only one isomeric structure, but this would 
not truely reflect the right 3D-demands at the receptor.  

I am thankful for any information or ideas on this problem.
 
Cheers!

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