Department of Chemistry, McGill University, Montréal, QC H3A 0B8, Canada.
Department of Chemistry, McGill University, Montréal, QC H3A 0B8, Canada
Proc Natl Acad Sci U S A. 2021 Jul 20;118(29). doi: 10.1073/pnas.2026452118.
Less than 9% of the plastic produced is recycled after use, contributing to the global plastic pollution problem. While polyethylene terephthalate (PET) is one of the most common plastics, its thermomechanical recycling generates a material of lesser quality. Enzymes are highly selective, renewable catalysts active at mild temperatures; however, they lack activity toward the more crystalline forms of PET commonly found in consumer plastics, requiring the energy-expensive melt-amorphization step of PET before enzymatic depolymerization. We report here that, when used in moist-solid reaction mixtures instead of the typical dilute aqueous solutions or slurries, the cutinase from can directly depolymerize amorphous and crystalline regions of PET equally, without any pretreatment, with a 13-fold higher space-time yield and a 15-fold higher enzyme efficiency than reported in prior studies with high-crystallinity material. Further, this process shows a 26-fold selectivity for terephthalic acid over other hydrolysis products.
在使用后，只有不到 9%的塑料得到回收，这导致了全球塑料污染问题。虽然聚对苯二甲酸乙二醇酯 (PET) 是最常见的塑料之一，但它的热机械回收会产生质量较低的材料。酶是高度选择性的可再生催化剂，在温和的温度下具有活性；然而，它们对常见于消费类塑料中的更具结晶形式的 PET 缺乏活性，这需要对 PET 进行能量密集型的熔融-非晶化步骤，然后才能进行酶解聚合。我们在这里报告，当在潮湿的固-液反应混合物中使用时，而不是典型的稀水溶液或浆料，来自 的角质酶可以直接对 PET 的无定形和结晶区域进行同等的解聚，无需任何预处理，时空产率比以前研究中使用高结晶度材料提高了 13 倍，酶效率提高了 15 倍。此外，该过程对苯二甲酸的选择性是其他水解产物的 26 倍。
