Earth is flooded with plastics and the need for sustainable recycling strategies for polymers has become increasingly urgent. Enzyme‐based hydrolysis of post‐consumer plastic is an emerging strategy for closed‐loop recycling of polyethylene terephthalate (PET). The polyester hydrolase PHL7, isolated from a compost metagenome, completely hydrolyzes amorphous PET films, releasing 91 mg of terephthalic acid per hour and mg of enzyme. Vertical scanning interferometry shows degradation rates of the PET film of 6.8 μm h−1. Structural analysis indicates the importance of leucine at position 210 for the extraordinarily high PET‐hydrolyzing activity of PHL7. Within 24 h, 0.6 mgenzyme gPET−1 completely degrades post‐consumer thermoform PET packaging in an aqueous buffer at 70 °C without any energy‐intensive pretreatments. Terephthalic acid recovered from the enzymatic hydrolysate is then used to synthesize virgin PET, demonstrating the potential of polyester hydrolases as catalysts in sustainable PET recycling processes with a low carbon footprint.
The accelerating and inhibiting effects of nanoparticles on amyloid peptide aggregation are discussed for varying nanoparticle and peptide properties in the context of recent studies.
11 August 2016 in Angewandte Chemie International Edition
The question of how amyloid fibril formation is influenced by surfaces is crucial for a detailed understanding of the process in vivo. We applied a combination of kinetic experiments and molecular dynamics simulations to elucidate how (model) surfaces influence fibril formation of the amyloid‐forming sequences of prion protein SUP35 and human islet amyloid polypeptide. The kinetic data suggest that structural reorganization of the initial peptide corona around colloidal gold nanoparticles is the rate‐limiting step. The molecular dynamics simulations reveal that partial physisorption to the surface results in the formation of aligned monolayers, which stimulate the formation of parallel, critical oligomers. The general mechanism implies that the competition between the underlying peptide–peptide and peptide–surface interactions must strike a balance to accelerate fibril formation.