en.Wedoany.com Reported - A European research team recently published a study in the journal Crystals, exploring the application of heat-resistant enzymes in the recycling of polyethylene terephthalate (PET). PET is widely used in packaging and textiles, and its recycling process typically requires efficient depolymerization technology. The study shows that at temperatures close to 70°C, PET polymers become more accessible, enabling efficient depolymerization. Under these conditions, enzymes must maintain structural integrity and active site flexibility, a combination that poses a challenge for enzyme design.
The research team analyzed cutinases derived from the thermophilic fungus Chaetomium thermophilum, including the wild-type enzyme (CtCutWT) and a mutant variant (CtCutS136A). Structural characterization and thermal stability measurements were performed in the range of 30°C to 100°C using differential scanning calorimetry. The enzyme adopts an α/β-hydrolase fold, forming a stable framework, while a flexible lid-like loop covers the active site, regulating substrate access. Structural observations indicate that this loop undergoes conformational changes upon ligand binding, facilitating catalytic function without compromising overall stability.
The detection of chloride ions near the active site suggests the presence of a positively charged microenvironment, which may promote substrate interactions. Thermal analysis revealed a two-stage unfolding process: initial structural changes begin around 60°C, and a second transition occurs between 65°C and 70°C. These findings support the concept that different regions of the enzyme possess distinct thermal stabilities, reflecting the notion of functional partitioning within the protein.
The results indicate that effective enzymes for PET biorecycling may require a combination of a stable core structure and localized flexibility at the catalytic interface. This structural design supports both thermostability and enhanced substrate adaptability, providing a foundation for developing improved enzymes for industrial plastic recycling. The study was published in the journal Crystals (Volume 16, Special Issue 4) on March 24, 2026, and has the potential to contribute to the advancement of global plastic recycling technologies.
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