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InChI Markush and Variability Jonathan M. Goodman, Gerd Blanke, István Öri & Anthony Baston PDF of Presentation given during NIH Virtual Workshop on InChI, March 22, 2021

Tautomers in InChI NIH InChI Workshop, March 22, 2021 https://cactus.nci.nih.gov/presentations/NIHInChI_2021-03/Day_1_Nicklaus_Tautomerism_2021-03-21A.pdf Presentation by Marc C. Nicklaus Redesign of Handling of Tautomerism for InChI V2 IUPAC Project 2012-023-2-800  

Tautomerizer – Predict tautomers based on 80+ rules https://cactus.nci.nih.gov/tautomerizer/ Introduction from Web Service (11/24/2022): Experimental service that allows you to test a set of tautomeric transforms with your own molecules. The predefined set of transforms comprises both the current 24 standard rules used by the chemoinformatics toolkit CACTVS and 55+ additional rules compiled in the context of […]

Enumeration of Ring–Chain Tautomers Based on SMIRKS Rules Laura Guasch, Markus Sitzmann, and Marc C. Nicklaus https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4170818/ J Chem Inf Model. 2014 Sep 22; 54(9): 2423–2432. Abstract: A compound exhibits (prototropic) tautomerism if it can be represented by two or more structures that are related by a formal intramolecular movement of a hydrogen atom from […]

Tautomerism of Warfarin: Combined Chemoinformatics, Quantum Chemical, and NMR Investigation Laura Guasch, Megan L. Peach, and Marc C. Nicklaus https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7724503/ J Org Chem. 2015 Oct 16; 80(20): 9900–9909. Abstract: Warfarin, an important anticoagulant drug, can exist in solution in 40 distinct tautomeric forms through both prototropic tautomerism and ring–chain tautomerism. We have investigated all warfarin […]

Experimental and Chemoinformatics Study of Tautomerism in a Database of Commercially Available Screening Samples Laura Guasch, Waruna Yapamudiyansel, Megan L. Peach, James A. Kelley, Joseph J. Barchi, Jr., and Marc C. Nicklaus https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5129033/ J Chem Inf Model. 2016 Nov 28; 56(11): 2149–2161. Abstract: We investigated how many cases of the same chemical sold as different products […]

Tautomerism in large databases Markus Sitzmann, Wolf-Dietrich Ihlenfeldt, and Marc C. Nicklaus https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2886898/ Journal of Computer-Aided Molecular Design volume 24, pages521–551 (2010) https://link.springer.com/article/10.1007/s10822-010-9346-4#Ack1   Abstract: We have used the Chemical Structure DataBase (CSDB) of the NCI CADD Group, an aggregated collection of over 150 small-molecule databases totaling 103.5 million structure records, to conduct tautomerism analyses on one of […]

Tautomer Database: A Comprehensive Resource for Tautomerism Analyses Devendra K. Dhaked, Laura Guasch, and Marc C. Nicklaus https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8456363/   Abstract: We report a database of tautomeric structures that contains 2819 tautomeric tuples extracted from 171 publications. Each tautomeric entry has been annotated with experimental conditions reported in the respective publication, plus bibliographic details, structural identifiers […]

Toward a Comprehensive Treatment of Tautomerism in Chemoinformatics Including in InChI V2 Devendra K. Dhaked, Wolf-Dietrich Ihlenfeldt, Hitesh Patel, Victorien Delannée, and Marc C. Nicklaus* https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8459712/ Abstract: We have collected 86 different transforms of tautomeric interconversions. Out of those, 54 are for prototropic (non-ring–chain) tautomerism, 21 for ring–chain tautomerism, and 11 for valence tautomerism. The majority […]

Crowdsourced Evaluation of InChI-based Tautomer Identification precisionFDA Challenge https://precision.fda.gov/challenges/29 Challenge Time Period November 1, 2022 – March 1, 2023 This challenge focuses on the International Chemical Identifier (InChI), which was developed and is maintained under the auspices of the International Union of Pure and Applied Chemistry (IUPAC) and the InChI Trust. The InChI Trust, the IUPAC […]

Abstract Background: PubChem is a chemical information repository, consisting of three primary databases: Substance, Compound, and BioAssay. When individual data contributors submit chemical substance descriptions to  substance, the unique chemical structures are extracted and stored into Compound through an automated process called structure standardization. The present study describes the PubChem standardization approaches and analyzes them […]

Abstract Background: Over the past several centuries, chemistry has permeated virtually every facet of human lifestyle, enriching fields as diverse as medicine, agriculture, manufacturing, warfare, and electronics, among numerous others. Unfortunately, application-specific, incompatible chemical information formats and representation strategies have emerged as a result of such diverse adoption of chemistry. Although a number of efforts […]

Abstract Background: The Blue Obelisk movement was established in 2005 as a response to the lack of Open Data, Open Standards and Open Source (ODOSOS) in chemistry. It aims to make it easier to carry out chemistry research by promoting interoperability between chemistry software, encouraging cooperation between Open Source developers, and developing community resources and […]

Abstract Background: There are two line notations of chemical structures that have established themselves in the field: the SMILES string and the InChI string. The InChI aims to provide a unique, or canonical, identifier for chemical structures, while SMILES strings are widely used for storage and interchange of chemical structures, but no standard exists to […]

Abstract An algorithm is introduced that enables a fast generation of all possible prototropic tautomers resulting from the mobile H atoms and associated heteroatoms as defined in the InChI code. The InChI-derived set of possible tautomers comprises (1,3)-shifts for open-chain molecules and (1,n)-shifts (with n being an odd number >3) for ring systems. In addition, our algorithm […]

Abstract A modified InChI (International Chemical Identifier) string scheme, yaInChI (yet another InChI), is suggested as a method for including the structural information of a given molecule, making it straightforward and more easily readable. The yaInChI theme is applicable for checking the structural identity with higher sensitivity and generating three-dimensional (3-D) structures from the one-dimensional […]

Abstract UniChem is a low-maintenance, fast and freely available compound identifier mapping service, recently made available on the Internet. Until now, the criterion of molecular equivalence within UniChem has been on the basis of complete identity between Standard InChIs. However, a limitation of this approach is that stereoisomers, isotopes and salts of otherwise identical molecules […]

Abstract This paper documents the design, layout and algorithms of the IUPAC International Chemical Identifier, InChI.

Abstract IUPAC Standards Online is a database built from IUPAC’s (The International Union of Pure and Applied Chemistry) standards and recommendations, which are extracted from the journal Pure and Applied Chemistry (PAC). The International Union of Pure and Applied Chemistry (IUPAC) is the organization responsible for setting the standards in chemistry that are internationally binding […]

Abstract Learn about technology that solves the issue of interpreting 3D stereochemical information implied in 2D structure representations.

Abstract The IUPAC International Chemical Identifier (InChI) is a non-proprietary, machine-readable chemical structure representation format enabling electronic searching, and interlinking and combining, of chemical information from different sources. It was developed from 2001 onwards at the U.S. National Institute of Standards and Technology under the auspices of IUPAC’s Chemical Identifier project. Since 2009, the InChI […]

Project for Cheminformatics Fall 2012. Part 2/2. Presentation on encodings, SMILES and InChI.

Abstract Optimal descriptors calculated with International Chemical Identifier (InChI) have been used to construct one-variable model of the solubility of fullerene C60 in organic solvents . Attempts to calculate the model for three splits into training and test sets gave stable results.

This presentation is a part of Google Tech Talks which was added to the GoogleTalksArchive on August 22, 2006. The original presentation date took place on November 2, 2006. ABSTRACT (Imported From YouTube Source) The central token of information in Chemistry is a chemical substance, an entity that can often be represented as a well-defined […]

This document contains a brief intro to InChI suitable for undergraduate students and two exercises, with answer keys. The first assignment asks about the information encoded in a sample InChI. The last question in this assignment asks students to use the InChI Key as a search term – this will be a lot easier to […]