木质素过氧化物酶降解四环素机理的研究

摘要

To study the mechanism of tetracycline antibiotics degradation by peroxidase,this paper chooses the crude enzyme of lignin peroxidase (LiP)from Phanerochaete chrysosporium as the research obj ect,and explores the induction conditions of lignin peroxidase and degradation mechanism of tetracycline (TC).The results indicate that the limitation of carbon,nitrogen and low concertation of Mn2+ are important factors for enzyme production.The degradation reaction of TC terminates when the concentration of H2 O2 decreases to 0.045 mmol/L,and the degra-dation rate reaches 82%within 10 min.LiP is still effective by adding TC and H2 O2 when degradation reaction rea-ches balance,and the secondary degradation rate is 65%.Lignin peroxidase has a strong ability of TC degradation with different initial concentrations (10 mg/L,25 mg/L,50 mg/L,100 mg/L),the degradation rate being 62%, 80%,82% and 90%respectively.According to oxford cup tests,the transformation products of TC show lower an-timicrobial potencies than the parent compound.There are six possible transformation products,namely,E-TC,TP 461,E-TP 461,TP 477,TP 475 and TP 445 using LC/MS in the progress of TC degradation by LiP.Besides,the paper infers the potential degradation pathway of TC by LiP.%为探究过氧化物酶对四环素类抗生素的降解机理，以白腐真菌Phanerochaetechrysosporium表达的木质素过氧化物酶（LiP）粗酶为研究对象，研究其产酶条件及其降解四环素（TC）的机理。结果表明：低浓度 Mn2＋可促进产酶，碳源、氮源限制是产酶的重要条件；降解反应进行10 min后，H2 O2消耗至阈值0．045 mmol／L，LiP 对TC的降解停止，其降解率达到82％；TC降解反应趋于平衡时，补加TC和 H2 O2后，LiP依然可以高效发挥作用，其二次降解率达到65％；LiP作用于不同初始浓度（10 mg／L、25 mg／L、50 mg／L、100 mg／L）TC，显示LiP 对不同浓度TC均可有效降解，TC降解率分别为62％、80％、82％和90％；降解产物的抑菌性试验反映出降解产物较TC母体的抑菌性明显降低；LC／MS捕获到6种可能的降解产物E-TC、TP 461、E-TP 461、TP 477、TP 475和TP 445，并推测出LiP降解TC可能的降解途径。