Fabrication of Ni2+-nitrilotriacetic acid functionalized magnetic mesoporous silica nanoflowers for one pot purification and immobilization of His-tagged ω-transaminase

omega-transaminase (omega-TA) has gained much attention due to its application in the preparation of chiral amines. It is of increasing interest to obtain stable and reusable immobilized omega-TA for economic catalytic process. A major approach for simple and efficient immobilization is introduction of an affinity tag to the target enzyme. Thus, in this study, the recombinant omega-TA with His-tag was successfully expressed in E.coli Rosetta (DE3). To realize the one pot purification and immobilization of omega-TA, Ni2+-nitrilotriacetic acid functionalized magnetic mesoporous silica nanoflowers (Ni-NTAIMMS-NF) were synthesized for the first time. The morphology, structure, and composition of the Ni-NTA/MMS-NF were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, etc. The immobilized omega-TA had the same optimum temperature with free omega-TA, and the optimum pH of the immobilized omega-TA was shifted from 7.5 to 7.0. Compared to free omega-TA, the immobilized omega-TA showed increased thermal stability, better pH stability, and excellent storage stability. Additionally, the immobilized omega-TA preserved 67.38% of initial activity after reusing twelve times. These results revealed that Ni-NTA/MMS-NF might have great potential in the purification and immobilization of His-tagged enzyme. (C) 2017 Elsevier B.V. All rights reserved.