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 amino acid derivative resulting from reaction of alanine at the amino group or the carboxy group, or from the replacement of any hydrogen of phenylalanine by a heteroatom. The definition normally excludes peptides containing phenylalanine residues.