What are InChI and InChIKey?

Content:

What is an InChI?

The International Union of Pure and Applied Chemistry (IUPAC) developed the InChI (International Chemical Identifier") standard, a textual representation of chemical substances, to provide a standard way to encode molecular information and to facilitate the search for such information in databases and on the web.

InChI is made of layers. InChI can be seen as a barcode to uniquely identify chemical structures.

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What is an InChIKey?

The condensed InChIKey is a hashed version of the full InChI (created using the SHA-256 algorithm). It was designed for easy web searches of chemical compounds.

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An InChIKey can be used to quickly match identical structures or those that differ only in charge or stereochemistry.

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Further readings

InChIKey in Rhea

When the 2D structure or a reaction participant is fully defined, its InChIKey is provided in the Reaction participants section.

You can search Rhea reactions by using a full or partial InChIKey.