β-alanine: an amino acid produced by aspartate 1-decarboxylase and a precursor to coenzyme A[6] and the peptides carnosine and anserine. γ-Aminobutyric acid (GABA): a neurotransmitter in animals. δ-Aminolevulinic acid: an intermediate in tetrapyrrole biosynthesis (haem, chlorophyll, cobalamin etc.).