The SULT1A3 enzyme was chosen for this study for two reasons.First, it is an enzyme that is crucial to the life cycle of dopaminergicdrugs, such as those used for treating Parkinson’s disease.One of the current authors has studied these types of molecules extensively,2 including in the SULT1A3 enzyme.3 Second, the binding site is of a reasonable size to performthree- and four-body calculations (10 amino acid residues, leadingto 45 three-body energy terms) and contains an equal mixture of chargedand polar amino acid residues (five) and nonpolar amino acid residues(five). Here, SULT1A3 is linked to Parkinson disease.