Degradation of a Main Plastic Pollutant Polyethylene Terephthalate by Two Distinct Proteases (Neprilysin and Cutinase-like Enzyme).

In this DFT study, hydrolysis of polyethylene terephthalate (PET), a major cause of plastic pollution, by two distinct enzymes, neprilysin (, a mononuclear metalloprotease) and cutinase-like enzyme (, a serine protease), has been investigated. These enzymes utilize different mechanisms for the degradation of PET. uses either the metal-bound hydroxide attack (MH) mechanism or reverse protonation (RP) mechanism, while utilizes a general acid/base mechanism that includes acylation and deacylation processes. Additionally, the RP mechanism of can proceed through three pathways, RP0, RP1, and RP2. The DFT calculations predict that, among all these mechanisms, the MH mechanism is the energetically most favorable one for the enzyme. In comparison, catalyzes this reaction with a significantly higher barrier. These results suggest that the Lewis acid and nucleophile activations provided by the Zn metal center of are more effective than the hydrogen bonding interactions afforded by the catalytic Ser85-His180-Asp165 triad of . They have provided intrinsic details regarding PET degradation and will pave the way for the design of efficient metal-based catalysts for this critical reaction.