Li Xia, Li Jianpeng, Hao Sijia, Han Ailing, Yang Yayu, Fang Guozhen, Liu Jifeng, Wang Shuo
State Key Laboratory of Food Nutrition and Safety, Tianjin University of Science and Technology, Tianjin, 300457, PR China.
School of Food Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong, 250353, PR China.
J Hazard Mater. 2021 Feb 5;403:123873. doi: 10.1016/j.jhazmat.2020.123873. Epub 2020 Sep 7.
Di(2-ethylhexyl) phthalate (DEHP), the most abundantly used plasticizer, was considered to be a hazardous chemical that was difficult to be degraded naturally. In this study, inspired by the "catalytic triad'' in serine proteases, an enzyme mimic material was developed by combining the proteases's active sites of serine, histidine and aspartate (S-H-D) with the self-assembling sequence of LKLKLKL and the aromatic group of fluorenylmethyloxycarbonyl (Fmoc). By mixing the monomer of peptides containing separate S, H and D residues with a ratio of 2:1:1, the enzyme mimics were found to co- assemble into nanofibers (Co-HSD) and showed the highest activity towards DEHP degradation because of the synergistic effects of active sites, orderly secondary structure and stable molecular conformation. To further improve ability and applicability, the high active mimetic enzyme was immobilized onto regenerated cellulose (RC) membranes for DEHP degradation in a continuous recycling mode. The RC membranes were first functionalized by the NaIO oxidation method to form aldehyde groups and then conjugated with the enzyme mimics via Schiff-base reaction. As a biocatalytic membrane, this membrane could not only effectively degrade DEHP, but also showed good stability, thus establishing a promising biomaterial for large scale biodegradation of DEHP in water decontamination and liquid food depollution.
邻苯二甲酸二（2-乙基己基）酯（DEHP）是使用最广泛的增塑剂，被认为是一种难以自然降解的有害化学物质。在本研究中，受丝氨酸蛋白酶中“催化三联体”的启发，通过将丝氨酸、组氨酸和天冬氨酸（S-H-D）的蛋白酶活性位点与LKLKLKL的自组装序列和芴甲氧羰基（Fmoc）的芳香基团相结合，开发了一种酶模拟材料。通过将含有单独S、H和D残基的肽单体按2:1:1的比例混合，发现酶模拟物共同组装成纳米纤维（Co-HSD），由于活性位点、有序二级结构和稳定分子构象的协同作用，对DEHP降解表现出最高活性。为了进一步提高能力和适用性，将高活性模拟酶固定在再生纤维素（RC）膜上，以连续循环模式降解DEHP。RC膜首先通过NaIO氧化法进行功能化以形成醛基，然后通过席夫碱反应与酶模拟物结合。作为一种生物催化膜，该膜不仅能有效降解DEHP，还表现出良好的稳定性，从而为水净化和液体食品去污染中大规模生物降解DEHP建立了一种有前景的生物材料。
