Enzyme catalysis is the acceleration of a chemical reaction by an enzyme through interactions that reduce the free-energy barrier to reaction. The active-site environment positions reacting groups and provides electrostatic stabilization of configurations along the reaction pathway. Networks of interacting residues and protein motions can couple substrate binding to changes in the catalytic region ^[1][2]. Catalytic turnover comprises substrate association, chemical conversion, and product release. Transition-state stabilization, proton or electron transfer, and quantum-mechanical contributions can have different roles in particular reactions ^[3]. The spatial arrangement of the active site also constrains which substrates and product configurations are accessible. Changes in enzyme sequence or structure can therefore alter catalytic activity and selectivity, and multiple enzyme-catalyzed steps can be connected into a reaction pathway ^[4].