Acceleration of Enzymatic Degradation of Poly(ethylene terephthalate) by Surface Coating with Anionic Surfactants

Enzymatic degradation of poly(ethylene terephthalate) (PET) is promising because this process is safer than conventional industrial approaches. Recently, a cationic PET hydrolase (PETase) was identified from Ideonella sakaiensis. Pre-incubation of a low-crystallinity PET film with anionic surfactants prior to initiating the reaction was found to improve PETase activity 120-fold. After 36 h at 30 °C, the film thickness decreased by 22 %. The binding of surfactants to the film makes the surface anionic, thereby attracting the cationic PETase. Mutagenesis of PETase showed that the surface cationic region formed by R53, R90, and K95, which are located on the same side as the substrate binding pocket, was crucial for efficient acceleration of activity by the anionic surfactant. Thus, surfactant bound on PET aligns the orientation of the active site to the surface, resulting in efficient hydrolysis. We believe that this approach using PETase could be further improved by designing surfactant molecules for the more efficient enzymatic PET degradation.