InChIKey - InChI Hash String

This section provides a quick introduction of InChI Key, which is generated from hash values of the InChI string.

InChIKey - InChIKey is a condensed version of the InChI string of a chemical substance, developed under the auspices of IUPAC (International Union of Pure and Applied Chemistry).

Technically, an InChIKey is 27-character long. It consists of three parts separated by hyphens, of 14, 10 and one character(s), in the format of XXXXXXXXXXXXXX-YYYYYYYYFV-P, where:

Theoretically, InChIKey is not unique for each chemical substance. But the likelihood of duplicates is very very small.

For a given molecule, the InChI key can be generated through a set of rules, which are not so easy to follow. So you should use some software tools to help you, like the free "InChI Software" provided at

Open Babel can also be used to generate the InChI string for any given molecule.

Here is a list of InChI Keys of some molecules.

Common     InChI
Name       Key
------     ------

You can use to find the InChI Key of a given molecule.

Table of Contents

 About This Book

 Introduction of Molecules

Molecule Names and Identifications

 Molecule Common Names

 InChI (International Chemical Identifier)

InChIKey - InChI Hash String

 IUPAC Nomenclature

 Canonical SMILES

 Molecule Mass and Weight

 Protein and Amino Acid

 Nucleobase, Nucleoside, Nucleotide, DNA and RNA

 Gene and Chromosome

 Protein Kinase (PK)

 DNA Sequencing

 Gene Mutation

 SDF (Structure Data File)

 PyMol Installation

 PyMol GUI and CLI

 PyMol Selections

 PyMol Editing Functions

 PyMol Measurement Functions

 PyMol Movie Functions

 PyMol Python Integration

 PyMol Object Functions

 ChEMBL Database - European Molecular Biology Laboratory

 PubChem Database - National Library of Medicine

 PDB (Protein Data Bank)

 INSDC (International Nucleotide Sequence Database Collaboration)

 HGNC (HUGO Gene Nomenclature Committee)

 Relocated Tutorials

 Resources and Tools

 Molecule Related Terminologies


 Full Version in PDF/EPUB