结合分子模拟探讨不同醚键PBS基共聚物的性能与酶催化降解

Performance of PBS-based Copolymer Containing Different Ether Bond and Its Enzymatic Degradation by Molecular Simulation

以硫二甘醇取代二甘醇,在聚(丁二酸丁二醇酯)(PBS)分子主链上分别引入硫醚和氧醚基团,得到聚(丁二酸丁二醇酯-丁二酸硫代二乙二醇酯)[P(BS-co-TDGS)]和聚(丁二酸丁二醇酯-丁二酸二乙二醇酯)[P(BS-co-DEGS)],通过热重分析(TG)和X射线衍射(XRD)测试比较了二者的结晶性能和热性能.采用南极假丝酵母脂肪酶N435(CALB)为催化剂,在水相中研究了P(BS-co-TDGS)和P(BS-co-DEGS)的降解规律及差异性.采用分子模拟方法研究了共聚物可能存在的聚集态以及N435酶与底物的结合,模拟结果验证了共聚物P(BS-co-TDGS)的结晶度下降及热稳定性降低的结论.分子对接模拟结果表明,N435酶与DEGSDEG单元的结合能更大,即含有丁二酸硫代二乙二醇酯键型底物P(BS-co-DEGS)与N435酶活性位点的对接更为稳定.

Poly（butylene succinate-co-thiodiglycol succinate）[P（BS-co-TDGS）] and poly（butylene succi-nate-co-diglycol succinate ） [ P （ BS-co-DEGS ） ] were synthesized by incorporating thioether group and ether oxygen group to the main chain of poly（ butylene succinate） （ PBS） . Their thermal properties and crystallinity were compared by thermography analysis（ TG） and X-ray diffraction（ XRD） . The degradation and their differ-ences were studied in aqueous media with Candida antarctica lipase N435（CALB） as a catalyst. The possible state of aggregation of copolymers and the combination between N435 lipase and substrate were also studied by molecular simulation. The results verify that the crystallinity and thermal stability of P （ BS-co-TDGS ） de-crease. In addition, molecular docking simulation results show that the binding energy of N435 enzyme and di-ethylene glyol succinic-diethylene glyol（ DEGS-DEG） was larger. That is, the docking of substrate P（ BS-co-DEGS） containing ester bond such as thiodiglycol succinate with the active site of N435 lipase was more sta-ble.