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 N-acetyl-amino acid in which the amino acid specified is L-ornithine. If R1 is the acetyl group and R2 is a hydrogen then the molecule is N(5)-acetylornithine. If R1 is a hydrogen and R2 is acetyl group then the molecule is N(2)-acetylornithine.