Diseño de la variante mutante W159H de la enzima PETasa de Ideonella sakaiensis

Abstract

The sustained increase in the production and consumption of polyethylene terephthalate (PET) has led to a significant accumulation of plastic waste that is difficult to manage, for which conventional recycling routes have technical and energy limitations. In this context, biodegradation mediated by PET hydrolase enzymes is emerging as a complementary alternative for the depolymerization of post-consumer PET. Ideonella sakaiensis PETase (IsPETase) stands out for its ability to act on semi-crystalline PET under moderate conditions; however, its activity and thermal stability are still insufficient for pre-industrial scale applications. The objective of this work was to design and evaluate the W159H mutant variant of the PETase enzyme from I. sakaiensis in order to improve its catalytic performance against post-consumer PET bottles. The point mutation W159H was introduced into the M3 variant of IsPETase, cloned into the pET-30a(+) vector, expressed in Escherichia coli Rosetta, and characterized by SDS-PAGE. Activity was evaluated by incubating micronized PET pellets at 50 degrees Celsius and pH 9.4, quantifying the loss of polymer mass. The W159H variant achieved a 44.9 percent degradation of the initial 125.2 milligrams of PET, demonstrating competitive catalytic performance. The results demonstrated that the W159H substitution represents a relevant optimization point of the IsPETase aromatic clamp and provides experimental evidence serving as a basis for the rational design of multiple variants aimed at the biological recycling of PET waste.