中文摘要：

采用固定化洋葱假单胞菌（PC）脂肪酶为催化剂,研究了在氯仿和四氢呋喃（THF）中不同摩尔比的聚（丁二酸丁二醇-co-丁二酸己二醇酯）（PBSH）的酶促降解规律及其差异性.通过PBSH降解前后的相对分子质量变化、降解产物的MALDI-TOF-MS分析研究了共聚酯降解规律,并以分子动力学（MD）及分子对接模拟分别研究了PC酶的溶剂效应及酶与底物的结合机制.研究结果表明,PC酶在2种溶剂中均可催化PBSH降解,但在氯仿中酶的活性较大,PBSH降解率大.分子动力学模拟数据表明,在THF中,PC酶整体氨基酸残基的涨落比氯仿中大,且THF会进入酶活性口袋中与催化残基Ser87结合,破坏了催化残基Ser87和His286之间的相互作用.分子对接结果分析发现,含丁二酸己二醇酯（HS）单元底物与PC酶活性位点的对接比含丁二酸丁二醇酯（BS）单元的更为稳定.

英文摘要：

The bio-catalysed cleavage of ester bonds in poly （butylene succinate-co-hexane succinate） （PBSH） was studied with the aim to gain more underlying information about the degradation rules and differences in chloroform and tetrahydrofuran. Among various hydrolytic enzymes the lipase from Pseudomonas cepacia （PC） was chosen for the studies. The rules of enzymatic degradation were investigated by molecular weight variation and MALDI-TOF-MS analysis of the degradation products. Additionally, solvent effect and mechanism of the combination between substrate and enzyme were studied with molecular dynamics （MD） simulations and molecular docking. The results suggested that PBSH showed an obvious degradation both in chloroform and tetrahydrofuran. Particularly higher activity of PC lipase and greater degradation of PBSH were observed in chloroform. Molecular dynamics simulations data showed that root mean square fluctuation （RMSF） of the whole residues of PC lipase in tetrahydrofuran was greater than that in chloroform. In tetrahydrofuran,the solvent molecules could reach the active site and interact intensively with the active residues Ser87. This interaction destroyed the hydrogen bonding between Ser87 and His286. According to the results of molecular docking, the substrate containing hexane succinate （HS） docked more stably in the enzyme active site than butylene succinate （BS）.