Design of a Novel Peptide with Esterolytic Activity toward PET by Mimicking the Catalytic Motif of Serine Hydrolases

Serine hydrolases have become increasingly important for recycling PET plastics. However, their properties are inherently constrained by their 3D structure, which in turn limits the conditions for their application. Considering peptides as catalysts for industrial depolymerization processes can help us to escape some of these limitations. In this article, a 25 amino acid thermostable peptide, HSH-25, was designed to depolymerize PET. The peptide incorporates a His-Ser-His motif, inspired by the catalytic triad found in the serine hydrolase family, into a β-hairpin fold. Stability of the fold was investigated by molecular dynamics simulations. Esterolytic activity of the peptide toward model substrates was detected within a pH range from pH 7 to pH 9.5. Degradation of polymeric PET substrates was confirmed by atomic force microscopy imaging on spin-coated PET thin films.