It is chemically similar to the artificial sweetener aspartame, but is used at vastly lower levels and is more stable.[5] Chemically, it has a 3,3-dimethylbutyl group attached to the amino group of the aspartic acid portion of the molecule. Peptidases, which would typically break the peptide bond between the aspartic acid and phenylalanine moieties, are effectively blocked by the presence of the 3,3-dimethylbutyl moiety, thus reducing the production of phenylalanine during metabolism of the chemical. As a result, it is safe for consumption by those who suffer from phenylketonuria