PETase learns from LCC: Redesigning enzymatic reactivity with probability-based simulations

Despite significant interest in enzymatic plastic degradation, the performance of currently available enzymes remains limited under industrial conditions. Addressing this requires approaches that identify the molecular features controlling catalytic efficiency and guide targeted enzyme engineering. Here, we simulate and compare the catalytic activity of PETase and LCC ICCG , two enzymes receiving considerable attention for degrading polyethylene terephthalate and related polyesters. PETase has a more accessible active site but moderate activity and thermal stability, while LCC ICCG exhibits superior efficiency at higher temperatures but a less accessible active site. Using an efficient enhanced sampling method based on the committor function, combined with electronic and structural analysis, we characterize how both enzymes operate and identify the molecular reasons for their different efficiencies. We translate these insights into a rational double mutation (W159H and I208V) that enhances PETase activity, shifting its mechanism toward that of LCC ICCG and potentially enabling efficient catalysis at lower temperatures.