Characterization and immobilization of arylsulfatase on modified magnetic nanoparticles for desulfation of agar

[Display omitted] •A low cost, simple manipulation and nontoxic approach were designed for the preparation of Carboxyl-functioned Magnetic Nanoparticles (CMNPs).•CMNPs were prepared and well characterized by Fourier transform infrared spedtroscopy and scanning electron microscope.•Arylsulfatase was successfully immobilized onto CMNPs and the catalysts exhibited good catalytic activity for the desulfation of agar.•The immobilized arylsulfatase can keep its catalytic activity after being reused seven times. Carboxyl functioned magnetic nanoparticles (CMNPs) were prepared by a simple co-precipitation method and characterized by Fourier transform infrared spedtroscopy and scanning electron microscope. The prepared CMNPs were used for covalent immobilization of the arylsulfatase which could be applied in desulfation of agar. The optimal immobilizaion conditions were obtained as follows: glutaraldehyde concentration 1.0% (v/v), cross-linking time 3h, immobilization time 3h, immobilization temperature 5°C and enzyme dose 0.62U. Increase in properties of the arylsulfatase such as optimum temperature and pH was observed after immobilization. Immobilization led to increased tolerance of enzyme to some metal ions, inhibitors and detergents. The Km and kcat of the immobilized enzyme for hydrolysis of p-NPS at pH 7.5 and at 50°C were determined to be 0.89mmol/L and 256.91s−1, respectively. The relative desulfuration rates of immobilized arylsulfatase maintained 61.7% of its initial desulfuration rates after seven cycles. After the reaction of agar with immobilized arylsulfatase for 90min at 50°C, 46% of the sulfate in the agar was removed. These results showed that the immobilization of arylsulfatase onto CMNPs is an efficient and simple way for preparation of stable arylsulfatase and have a great potential for application in enzymatic desulfation of agar.