Polyethylene terephthalate is one of the most widely used synthetic plastics. The accumulation of abandoned PET has brought an environmental problem. A recently reported PET hydrolase, PETase, displays an efficient decomposition to PET. Herein, we synthesized four PETase conjugates by modifying four types of monomers onto PETase, which were hydrophobic tert-butyl methacrylate (TBMA), hydrophilic hydroxyethyl methacrylate (HEMA), positively charged 2-(dimethylamino)ethyl methacrylate (DMAEMA), and negatively charged methacrylic acid (MA). Despite the low modification with an average number of 3–5 monomers on each enzyme molecule, all the PETase conjugates exhibited improved enzyme activity, and thermal and pH stability. Particularly, the catalytic efficiency (k_cat/K_m) of TBMA-/DMAEMA-PETase toward bis-2(hydroxyethyl) terephthalate (BHET) increased 1.4 and 1.6-fold as compared with PETase. Characterizations by fluorescence and circular dichroism spectroscopy unraveled that the modification induced the structural transformations, including compact overall structure and opened substrate-binding pocket, which were in favor of the enhanced catalytic performance. Biodegradation against PET films by TBMA-/DMAEMA-PETase were 4.69 and 3.26-fold higher than PETase. The different catalytic performances of the enzyme conjugates for BHET and PET are considered due to the different interactions of the conjugates with the different substrates. The work demonstrated that the low modifications with hydrophobic and hydrophilic monomers were both effective in improving the catalytic performance toward PET degradation, especially for the hydrophobic and positively charged monomers.

聚对苯二甲酸乙二醇酯是应用最广泛的合成塑料之一。废弃PET的堆积带来了环境问题。最近报道的 PET 水解酶 PETase 显示出对 PET 的有效分解。在此，我们通过将四种单体修饰到 PETase 上合成了四种 PETase 偶联物，它们分别是疏水的甲基丙烯酸叔丁酯 (TBMA)、亲水的甲基丙烯酸羟乙酯 (HEMA)、带正电荷的甲基丙烯酸 2-(二甲氨基)乙酯 (DMAEMA) 和带负电荷的甲基丙烯酸 (MA)。尽管每个酶分子上平均有 3-5 个单体的低修饰，但所有 PETase 缀合物都表现出提高的酶活性以及热和 pH 稳定性。特别是催化效率（k _cat / K _m) TBMA-/DMAEMA-PETase 对双-2(羟乙基) 对苯二甲酸酯 (BHET) 与 PETase 相比增加了 1.4 和 1.6 倍。荧光和圆二色光谱表征表明，修饰诱导了结构转变，包括紧凑的整体结构和开放的底物结合口袋，这有利于提高催化性能。TBMA-/DMAEMA-PETase 对 PET 薄膜的生物降解比 PETase 高 4.69 和 3.26 倍。酶偶联物对 BHET 和 PET 的不同催化性能被认为是由于偶联物与不同底物的不同相互作用。研究表明，疏水性和亲水性单体的低改性均能有效提高对 PET 降解的催化性能，