In conclusion, our kinetic characterization of GtPyNP revealed the presence of a measurable activation heat capacity change Δ ‡ , which showed no significant dependence on medium pH or substrate charge. Experiments across a wide working space uncovered the remarkable effects of a single halide substitution which has a minor influence on Δ ‡ but conveys a significant kinetic effect by lowering the activation enthalpy, causing a >10fold rate increase. Therefore, our results present an important piece in the understanding of enzymatic systems across multidimensional working spaces where the choice of reaction conditions can affect rate, affinity and thermodynamic phenomena independently of one another. for tabulated data as well as the externally hosted Supporting Information for raw data and calculations.