The Chemical Entities of Biological Interest (ChEBI) ontology is downloaded weekly from EMBL-EBI at http://www.ebi.ac.uk/chebi/. The data is made available under the Creative Commons License (CC BY 3.0, http://creativecommons.org/licenses/by/3.0/). For more information see: Degtyarenko et al. (2008) ChEBI: a database and ontology for chemical entities of biological interest. Nucleic Acids Res. 36, D344–D350.
An organic group formed by removing one or more hydroxy groups from an oxoacid that has the general structure RkE(=O)l(OH)m (l =/= 0). Although the term is almost always applied to organic compounds, with carboxylic acid as the oxoacid, acyl groups can in principle be derived from other types of acids such as sulfonic acids or phosphonic acids.