carboxylic acid organonitrogen compound proteinogenic amino acid Any of the 23 alpha-amino acids that are precursors to proteins, and are incorporated into proteins during translation. The group includes the 20 amino acids encoded by the nuclear genes of eukaryotes together with selenocysteine, pyrrolysine, and N-formylmethionine. Apart from glycine, which is non-chiral, all have L configuration. CHEBI:83813 Wikipedia:Proteinogenic_amino_acid canonical amino acid canonical amino acids chebi_ontology proteinogenic amino acids