The choice of these system was solely based on the fact that reactivity of these mutants is already known using experimental site-directed mutagenesis . The electric field for the WT enzyme is found to be -0.327 V/Å (Figure ), and it is opposite to the C-O bond dipole vector illustrating that this EF would help the C-O bond to get polarized and could favor the reaction which is in accord with the QM/MM calculations. As shown in Figure and Figure , Arg90 forms a close and stable contact with the substrate and therefore, we anticipated a loss of EF due to the mutation of R90 with either Glycine or Alanine. along the reactive axis shows a linear correlation between the enzymatic electric field and reactivity of enzyme, therefore, EF along the reactive axis could be a descriptor for the enzymatic activity. The EF as a descriptor for enzymatic activity has computational advantage over other activation energy as the quantification of EF is very simple and easy. However, this perception is limited to CM and its different variants, therefore, we believe that a rigorous benchmarking of a correlation between EF along the reaction axis and enzymatic activity using different enzymesubstrate is needed in future studies.