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Where can I get InChIs with a fixed-hydrogen layer?

Asked by [ Admin ] , Edited by Egon Willighagen [ Admin ]

I was just looking at the structure of Azaguanine-8 (also at other places) and noted these two names:

  • 5-Amino-3H-[1,2,3]triazolo[4,5<wbr>-d]pyrimidin-7-ol
  • 5-amino-2,3-dihydro-7H-[1,2,3]triazolo[4,5-d]pyrimidin-7-one (depicted in 2D)

That seems to suggest we have names here for two tautomers (correct?). ChemSpider lists InChIs, but all without the fixed-hydrogen layer. Now, my use case involves knowing the exact tautomer, and was wondering if there are databases that provide InChIs for exact tautomers, so with this fixed-hydrogen layer. Where can I go?

NN comments
tony27587
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What information are you looking for associated with the structure? Are you looking to purchase it, property data etc? It will help identify where to look.

chem-bla-ics
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InChIs with the fixed-hydrogen layers enabled. It’s this InChI I am after.

tony27587
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Egon…how do you want to do the search to find the InChI? Are you expecting to search on the name “Azaguanine-8” and find all 7 tautomers? The reason I’m asking is in order to find the tautomers I think you have to draw them and if you draw them you may as well simply generate the InChIs directly?

chem-bla-ics
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A link to all tautomers know to the database would be nice, but I would be happy with just the InChI for the tautomer for the actual ChemSpider record I am looking at, preferably consistent with the 2D diagram, which does only show one tautomer. Each ChemSpider record shows one 2D diagram, which reflects one tautomer, right?

tony27587
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-bla-ics Egon…I take this as a request to insert onto ChemSpider an InChI with the fixed layer ON for the structure image shown ?

chem-bla-ics
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Yes, that would be brilliant! In fact, it would make ChemSpider more consistent: it makes clear what structure is shown in the 2D diagram, though this obviously also applies to the 3D diagram, and to most of your calculated properties further down the record…

tony27587
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-bla-ics We had a long discussion today about priorities for the near future. We have been working on a background processing framework where we can make mass changes across the database such as calculating properties offline and bulk deposition etc. This is a perfect test for that I think! Did my blog post make sense?

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2 answers

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markus.sitzmann [ Editor ]

Egon,


you can use our Resolver for this – first generate all InChIs:


and then for each InChI you can check for URLs where this structure is available, e.g:


Please note the filter option and set it to “exact”, which does exact structure matching – opposite is “parent” which searches via the canonical (or parent) tautomer.

To search tautomers in ChemSpider, use:


or if you want to start from a ChemSpider ID:


This loads the structure from ChemSpider, generates all tautomers and converts each tautomer back to its ChemSpider ID

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tony27587 [ Editor ]

This is a very useful and interesting question to examine what goes on with various databases in terms of storing tautomers etc. I have done a cursory examination of the situation and answered it on my blog in detail as it is a good educational piece.
http://www.chemconnector.com/chemunicating/different-approaches-to-storing-structures-and-inchis-on-chemspider.html

The answer to your question is that maybe ChemDB gives you what you need in terms of 6 tautomers out of the 7 possible. But you cannot find them by searching on the name,. You have to search ChemSPider then go through the data sources and look for the multiple link outs.

NN comments
chem-bla-ics
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ChemDB gives several Google hits… can you add a link for the one you mean?

tony27587
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-bla-ics I captured all the ChemDB hits in my blog post. You didn’t read it :–) ChemDB 4904712, 4148532, 6845191, 6691623, 6494441, 7232229

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