One-step immobilization-purification of enzymes by carbohydrate-binding module family 56 tag fusion.

Immobilization of enzymes is an essential strategy with outstanding prospects in biocatalytic processes. Nontoxic, inexpensive immobilized enzyme approach is especially important for food enzymes. We here demonstrate that a carbohydrate-binding module family 56 domain (CBM56-Tag) mediates the immobilization of fusion enzymes with the curdlan (β-1,3-glucan) particle support, thereby enabling the one-step immobilization-purification of target enzymes. CBM56-Tag exhibits an immunoglobulin-like β-sandwich fold, which can be adsorbed by curdlan via hydrogen bond-mediated binding. The maximum adsorption capacity of a fusion chitosanase (CBM56-GsCsn46A) on curdlan is 50.72 mg/g. The immobilized enzyme could be directly used in the packed-bed reactor. This immobilization strategy utilizes a natural polysaccharide without any treatment, avoiding the negative environmental effects. Moreover, the one step immobilization-purification simplifies the purification step, which reduces the use of chemicals. Our study provides a nontoxic and inexpensive immobilization strategy for the biocatalytic reaction in food industry.