has role gamma-aminobutyric acid histidine derivative imidazoles metabolite homocarnosine CHEBI:24607 N-(4-aminobutanoyl)histidine CHEBI:28050 A histidine derivative that is histidine in which one of the hydrogens attached to the alpha-amino group has been replaced by a 4-aminobutanoyl group. gamma-Aminobutyryl histidine CHEBI:5750 N-(4-aminobutyryl)histidine N-acyl-amino acid