A magnetic biocatalyst based on mussel-inspired polydopamine and its acylation of dihydromyricetin  

基于聚多巴胺的磁性纳米生物催化剂高效催化二氢杨梅素酰化（英文）

作　　者：邓啸 曹诗林[3,2] 李宁[2] 吴虹[2] Thomas J.Smithd 宗敏华[1,3] 娄文勇[1,2] 

机构地区：[1]华南理工大学制浆造纸工程国家重点实验室,广东广州510640 [2]华南理工大学食品科学与工程学院应用生物催化实验室,广东广州510640 [3]华南理工大学化学与化工学院,广东广州510640 [4]谢菲尔德哈勒姆大学生物分子科学研究中心

出　　处：《Chinese Journal of Catalysis》2016年第4期584-595,共12页催化学报（英文）

基　　金：supported by the National Natural Science Foundation of China(21336002,21222606,21376096);the Key Program of Guangdong Natural Science Foundation(S2013020013049);the Fundamental Research Funds for the Chinese Universities(2015PT002,2015ZP009);the Program of State Key Laboratory of Pulp and Paper Engineering(2015C04)~~

摘　　要：A support made of mussel-inspired polydopamine-coated magnetic iron oxide nanoparticles （PD-MNPs） was prepared and characterized. The widely used Aspetyillus niger lipase （ANL） was immobilized on the PD-MNPs （ANL@PD-MNPs） with a protein loading of 138 mg/g and an activity recovery of 83.6% under optimized conditions. For the immobilization, the pH and immobilization time were investigated. The pH and thermal and storage stability of the ANL@PD-MNPs significant- ly surpassed those of free ANL. The ANL@PD-MNPs had better solvent tolerance than free ANL. The secondary structure of free ANL and ANL@PD-MNPs was analyzed by infrared spectroscopy, A kinetic study demonstrated that the ANL@PD-MNPs had enhanced enzyme-substrate affinity and high catalytic efficiency. The ANL@PD-MNPs was applied as a biocatalyst for the regioselective acylation of dihydromyricetin （DMY） in DMSO and gave a conversion of 79.3%, which was higher than that of previous reports. The ANL@PD-MNPs retained over 55% of its initial activity after 10 cycles of reuse. The ANL@PD-MNPs were readily separated from the reaction system by a magnet. The PD-MNPs is an excellent support for ANL and the resulting ANL@PD-MNPs displayed good potential for the efficient synthesis of dihydromyricetin-3-acetate by enzymatic regioselective acylation.脂肪酶是一种三酰基甘油水解酶,目前广泛用于油脂化学、食品、有机合成和生物医药等领域.但是,游离脂肪酶在有机反应体系中容易失活,难以从反应体系中回收,导致其循环利用困难和生产成本增加.因此,需要对游离脂肪酶进行固定化,提高酶的稳定性和重复使用性,使其能够大规模用于工业生产.磁性四氧化三铁纳米粒子(MNPs)具有其超顺磁性和大比表面积等性质,但MNPs需表面修饰才能进一步应用.近年来,仿生矿化法制备的聚多巴胺纳米材料受到人们关注.在仿生矿化过程中,单体多巴胺经自聚合作用后形成聚多巴胺,该反应活性高,能对各类有机和无机纳米材料进行表面修饰.而且,聚多巴胺表层中的活性基团能与含有氨基和巯基的生物大分子发生迈克尔加成或席夫碱反应,从而将生物大分子固定在材料表面.本文利用聚多巴胺表面修饰MNPs,对所得聚多巴胺表面修饰的四氧化三铁纳米粒子(PD-MNPs)进行了结构表征.结果表明,PD-MNPs尺寸在14 nm左右.同时,成功将黑曲霉脂肪酶(ANL)固定在PD-MNPs上,结果显示在pH=8、固定化时间为12 h条件下,酶负载量为138 mg/g,酶活回收率达到83.6%,而且固定化酶的pH稳定性及热稳定性、储藏稳定性都优于游离酶.动力学研究表明,固定化酶Km值(63.2 mmol/L)低于游离酶(74.5 mmol/L),固定化酶的底物亲和性增强.进一步研究了固定化酶和游离酶在乙腈、二甲基亚砜、乙醇和[HMIm]BF_4这四种溶剂中的溶剂耐受性,结果显示固定化酶的耐受性均强于游离酶.采用红外光谱对游离酶和固定化酶二级结构的分析表明,游离黑曲霉脂肪酶经固定化后,α-螺旋和β-折叠含量分别增加了0.84%和2.74%,使得固定化后α-螺旋和β-折叠中存在的氢键能够更好地保持酶结构刚性,避免因结构改变而引起酶失活,增强了固定化酶在溶剂中的耐受性.二氢杨梅素是一种具有类黄酮结构�

关 键 词：Magnetic iron oxide Nanoparticle POLYDOPAMINE Aspergillus niger lipase DIHYDROMYRICETIN ACYLATION 

分 类 号：O621.251[理学—有机化学] O643.36[理学—化学]