Unusual depolymerization mechanism of Poly(ethylene terephthalate) by hydrolase 202

Polyethylene terephthalate (PET) waste significantly contributes to the global plastic crisis, but enzymatic conversion has become an efficient and environmentally friendly strategy to combat it. Therefore, this study explored the Re-face selective depolymerization mechanisms of a novel PET-degradation peptidase, hydrolase 202. Theoretical calculations revealed that the first step, a catalytic triad-assisted nucleophilic attack, is the rate-determining step. The corresponding Boltzmann-weighted average barrier was 21.6 kcal/mol. Furthermore, hydrolase 202 degraded Re-face PET more effectively than FAST-PETase, whereas other reported PET hydrolases (e.g., FAST-PETase) degraded Si-face PET more effectively. The hydrogen bond network significantly influenced the depolymerization efficiency. We also identified correlations between 24 important structural and charge features and energy barriers. Key charge, distance, and angle features were responsible for the superiority of the Re-face depolymerization. Finally, we identified residues that may affect the depolymerization efficiency of hydrolase 202, such as Glu215. These findings offer new insights into the potential engineering of PETases and may enhance enzymatic PET waste recycling.