CCL: How to identify duplicates for the same molecule that correspond to different tautomers or protonation states?

[Mikko Vainio <mikko.vainio()abo.fi>]

 Sent to CCL by: Mikko Vainio [mikko.vainio .. abo.fi]
 On 12/16/2010 05:19 PM, Gerard Pujadas gerard.pujadas:gmail.com wrote:
>  Dear CCL subscribers,
> I am interested in building a chemical database from different
>  chemical suppliers databases. One of the things that I would like to
>  avoid is the repetition of different structures in my database that
>  correspond to the same molecule (for instance, if in the database of
>  two different chemical suppliers the structure for the same molecule
>  is in a different tautomer or protonation state, I would like to
>  identify that they correspond to the same molecule). Any suggestion
>  about how to achieve this?
>  With many thanks in advances for your help
>  Yours sincerely
>  Gerard
 Dear Gerard,
The InChI program (http://www.iupac.org/inchi/) can be used to weed out
 duplicates in different databases. The InChI program does normalization
 of tautomeric states. The resulting identifier string includes a
 "charge
 layer" that you can easily ignore when doing comparisons. See also
 http://www.inchi-trust.org/
 Best regards,
 Mikko