Thermostability and Activity Improvements of PETase from <i>Ideonella sakaiensis</i>

Polyethylene terephthalate (PET), a widely used plastic, is a significant environmental pollutant due to its persistence. While the PET-degrading enzyme PETase from <i>Ideonella sakaiensis</i> offers promising solutions, its limited activity at higher temperatures hinders its practical application. This study aimed to enhance the PETase performance through protein engineering. We introduced multiple amino acid substitutions to the wild-type <i>I. sakaiensis</i> PETase to improve its thermostability, substrate binding, and catalytic activity. Several potential mutant IsPETases were generated using computational design and evaluated <i>in silico</i>. The selected mutant was then produced in <i>E. coli</i> BL21(DE3). Finally, the catalytic activity of the purified mutant IsPETase was examined <i>in vitro</i> using <i>p</i>-nitrophenyl butyrate and PET substrates. <i>Is</i>PETase^MT has been confirmed to be catalytically active and more thermostable with a maximum temperature reaching 60 °C and the <i>T</i> _m value increasing up to 15.3 °C compared to the wild-type PETase, <i>Is</i>PETase^WT. <i>Is</i>PETase^MT also showed better degradation toward the PET plastic film in comparison to <i>Is</i>PETase^WT. Thus, these findings demonstrate successful protein engineering to create a more robust PETase for potential plastic waste management applications.