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The dynamics of anion–quadrupole (or anion−π) interactions formed between negatively charged (Asp/Glu) and aromatic (Phe) side chains are for the first time computationally characterized in RmlC (Protein Data Bank entry 1EP0), a homodimeric epimerase. Empirical force field-based molecular dynamics simulations predict anion–quadrupole pairs and triplets (anion–anion−π and anion−π–π) are formed by the protein during the simulated trajectory, which suggests that the anion–quadrupole interactions may provide a significant contribution to the overall stability of the protein, with an average of −1.6 kcal/mol per pair. Some anion−π interactions are predicted to form during the trajectory, extending the number of anion–quadrupole interactions beyond those predicted from crystal structure analysis. At the same time, some anion−π pairs observed in the crystal structure exhibit marginal stability. Overall, most anion …