Laccase immobilization on the tailored cellulose-based Granocel carriers

Extracellular laccase produced by Cerrena unicolor was immobilized by adsorption or covalent bonds formation on the cellulose-based carrier Granocel. Immobilization was optimized by changing the anchor groups and the methods of activation/immobilization. On the base of measured activity and stability of immobilized preparations, the covalent method was selected. It was shown that coupling of the enzyme to the carrier via divinyl sulfone or glutaraldehyde yielded an enzyme–carrier preparation of high activity and storage stability. Further optimization of the carrier's superstructure consisted in changing pore diameters and amount of functional groups on the carriers surface. Three-fold higher activity was noted when the enzyme was immobilized on NH2-modified Granocel with the highest size exclusion limit and amino group content. Relatively low products sorption was observed on the carrier surface. The effects of protein concentration and pH-value of the coupling mixture on immobilization efficiency were evaluated also.