Synchronized purification and immobilization of his-tagged β-glucosidase via FeO/PMG core/shell magnetic nanoparticles.

In this paper, an efficient and convenient FeO/PMG/IDA-Ni nanoparticles that applied to purify and immobilize his-tagged β-glucosidase was synthesized, in which, FeO/PMG (poly (N, N'-methylenebisacrylamide-co-glycidyl methacrylate) core/shell microspheres were synthesized firstly using distillation-precipitation polymerization, then iminodiacetic acid (IDA) was used to open epoxy rings on the shell of microspheres to the combination of Ni. The gene of β-glucosidase that was from Coptotermes formosanus Shiraki was amplified, cloned into the expression vector pET28a with an N-terminal His-tag, and expressed in E.coli BL21. The nanoparticles showed the same purification efficiency as commercial nickel column which was a frequently used method in the field of purifying his-tagged proteins from crude cell lysates. The results indicated that FeO/PMG/IDA-Ni nanoparticles can be considered as an excellent purification material. β-glucosidase was immobilized on the surface of FeO/PMG/IDA-Ni to form FeO/PMG/IDA-β-glucosidase by means of covalent bound with imidazolyl and Ni. The immobilized β-glucosidase exhibited excellent catalytic activity and stabilities compared with free β-glucosidase. In addition, immobilized β-glucosidase can be recycled for many times and retain more than 65% of the original activity. The materials display enormous potential in the aspect of purifying and immobilizing enzyme.