Nickel-Carnosine complex: A new carrier for enzymes immobilization by affinity adsorption

Immobilization is an effective method to promote the application of enzyme industry for improving the stability and realizing recovery of enzyme. To some extent, the performance of immobilized enzyme depends on the choice of carrier material. Therefore, the development of new carrier materials has been one of the key issues concerned by enzyme immobilization researchers. In this work, a novel organic–inorganic hybrid material, nickel-carnosine complex (NiCar), was synthesized for the first time by solvothermal method. The obtained NiCar exhibits spherical morphology, hierarchical porosity and abundant unsaturated coordination nickel ions , which provide excellent anchoring sites for the immobilization of proteins. His-tagged organophosphate-degrading enzyme (OpdA) and ω-transaminase (ω-TA) were used as model enzymes to evaluate the performance of NiCar as a carrier. By a simple adsorption process , the enzyme molecules can be fixed on the particles of NiCar, and the stability and reusability are significantly improved. The analysis of protein adsorption on NiCar verified that the affinity adsorption between the imidazole functional group on the protein and the unsaturated coordination nickel ions on NiCar was the main force in the immobilization process, which provided an idea way for the development of new enzyme immobilization carriers.