Isolation, purification and partial characterization of the β-N-acetyl-D-glucosaminidase from the pupae of Helicoverpa armigera

β-N-acetyl-D-glucosaminidase (EC3.2.1.52) was purified from the pupae of Helicoverpa armigera by ammonium sulfate fractionation and chromatography on Sephadex G-200 and DEAE-cellulose. The purified enzyme preparation was homogeneous as judged by polyacrylamide gel electrophoresis. It was found that the specific activity of the enzyme was (2 678.79) U/mg. The optimal pH value was 5.63 and the optimal temperature 55℃. The enzyme was stable in the pH ranges of 4 to 8 under 37℃. The enzyme follows typical Michaelis-Menten kinetics for the hydrolysis of pNP-β-D-GlcNAc and the Km and Vm values were 0.16 mmol/L and 10.73 μmol·L~(-1)·min~(-1), respectively. The activation energy of the enzyme for the hydrolysis of pNP-β-D-GlcNAc was 66.24 kJ/mol.