▎ 摘　　要

Carboxyl-functionalized graphene oxide (GO-COOH) and amino-functionalized graphene oxide (GO-NH2) were prepared for use as carriers for alpha-amylase immobilization with 2-3% glutaraldehyde as a coupling agent. The alpha-amylase immobilized onto modified GO exhibited shifts in both working optimum pH and temperature with an increase from pH 6.0 to pH 7.0, and increased optimum temperature by 5-10 degrees C compared with the free enzyme. The loading capacity of the carriers is 786.8 mg/g (GO-COOH) and 437 mg/g (GO-NH2), respectively. The immobilized alpha-amylase exhibited a comparable stability activity in comparison with the free enzyme. The FT-IR spectra, UV-visible spectra as well as SEM analysis proved the presence of amine groups and carboxyl groups in the GO, and also covalent immobilization of a-amylase on the modified carrier. The constant values, the K-m was 3.541 mg.mL(-1), 4.072 mg.mL(-1) and 8.004 mg.mL(-1) for free enzymes, GO-COOH-E, and GO-NH2-E, respectively, and their V-max were 7.341 mg.mL(-1).min(-1), 4.968 mg.mL(-1).min(-1) and 6.655 mg.mL(-1.)min(-1), respectively. Furthermore, above 54% of the original activity of the immobilized enzyme was retained after 7 reaction cycles, indicating excellent reusability.