1	InChI The IUPAC International Chemical Identifier
2
3
4	Current Practice: Guanine
5	A Unique Chemical Substance Has a Unique, Natural Name Identify expressed as ‘connectivity’ Its nature may be expressed in different levels of specificity Creating a unique ‘name’ requires complex algorithms to convert connectivity to a ‘canonical’ string. InChI is proposed as such a public name
6	InChI Goal Provide a unique string representing a chemical substance of known structure Independent of specific depiction Derive from conventional ‘connection table’ Freely available Extensible
7	Outline Evolution Technical Points Current Usage Searching the Internet Extensions
8	InChI: NIST History NIST/EPA/NIH Mass Spectral Database (1976) 32,000 connection tables (1986) Structures & Properties (1990) Reference Data & Structure-Based Property Prediction NIST Chemistry Webbook (1991) http://webbook.nist.gov/ ‘Standard’ canonical connection table (1992) Internal use only NIST + IUPAC (2000)
9
10
11
12	Unplanned Extensions 2003-2006 Salts and H-migration Organometallics Protonation InChI -> Depiction Conformance test
13	http://www.iupac.org/inchi
14
15	International Chemical Identifier
16	Some Technical Details
17	Formal Requirement 1 Different compounds have different identifiers
18	Formal Requirement 2 One compound has only one identifier
19	Practical Requirements Simple text format Represent ‘equilibrated mixtures’ Account for incomplete stereo information Handle coordination/imprecise bonding Extensible
20
21	InChI Layers: L-Histidine
22	3 Steps to InChI Chemistry ‘Normalize’ Input Structure Implement chemical rules Math ‘Canonicalize’ (label the atoms) Equivalent atoms get the same label Format ‘Serialize’ Labeled Structure Output as character string (‘name’)
23	Normalization Divide input structure into ‘layers’ Each layer ‘refines’ structure Ignore ‘Electron Density’ Ignore bond type and charge location Stereochemistry sp² and sp³ only
24
25	Current Usage
26
27
28
29	Nick Day’s InChI FAQ
30	Illustration - Draw Compound
31	Generate InChI
32	Reverse InChI
33	Reversed Structure
34	Searching the Internet
35	"Results 1 - 8 of..." Results 1 - 8 of about 24 for “InChI=1/C6H8O6/c7-1-2(8)5-3(9)4(10)6(11)12-5/h2,5,7-10H,1H2”. (0.12 seconds) International Chemical Identifier - Wikipedia, the free encyclopedia ethanol, InChI=1/C2H6O/c1-2-3/h3H,2H2,1H3. Image:Ascorbic_acid.png L-ascorbic acid, InChI=1/C6H8O6/c7-1-2(8)5-3(9)4(10)6(11)12-5/h2,5,7-10H,1H2/t2-,5+/m0/s1 ... en.wikipedia.org/wiki/International_Chemical_Identifier - 18k - Cached - Similar pages L-ascorbic acid: Carcinogenic Potency Database InChI Code for l-Ascorbic acid: InChI=1/C6H8O6/c7-1-2(8)5-3(9)4(10)6(11)12-5/h2,5,7-10H,1H2/t2?,5-/m0/s1 Source for SMILES and InChI: USEPA Distributed ... potency.berkeley.edu/chempages/L-ASCORBIC%20ACID.html - 17k - Cached - Similar pages carcinogenic potency project s1 50-81-7 l-Ascorbic acid 176.1241 C6H8O6 OC([C@H]([C@H](O)CO)O1)=C(O)C1=O InChI=1/C6H8O6/c7-1-2(8)5-3(9)4(10)6(11)12-5/h2,5,7-10H,1H2/t2?,5-/m0/s1 ... potency.berkeley.edu/chemical-structures.text - 234k - Cached - Similar pages [ More results from potency.berkeley.edu ] International Chemical Identifier at AllExperts L-ascorbic acid, InChI=1/C6H8O6/c7-1-2(8)5-3(9)4(10)6(11)12-5/h2,5,7-10H,1H2/t2-,5+/m0/s1. Layer types. There are six InChI layer types: # Main layer ... experts.about.com/e/i/in/International_Chemical_Identifier.htm - 22k - Cached - Similar pages
36	Limitations in Searching Punctuation Misses structures Loses uniqueness Layering is inflexible Needs separate parser Depiction is lost Needs 2-d display module
37	Information Loss: replace punctuation with spaces
38	Extensions
39	Canonical Numbers Are Key Each number in a structure provides a precise way to connect other moieties. Unspecified atom/group Connection point, atom type, .. Predefined structural unit Sugars, polymers, … Markush series Substructure search queries
40	IUPAC vs InChI Atom Numbering
41	GLYDE-CT Glycan Data Exchange Format – Connection Table Carbohydrate structural data exchange Use InChI canonical numbers for building glycans from simple sugars http://lsdis.cs.uga.edu/~cory/GLYDE-v2_1-08-08-06.pdf
42
43	Depiction