Abstract:

An amidase from a strain Bacillus cereus ZJB-07112 was purified to homogeneity by using sonication, anion-exchange chromatography, phenyl-sepharose chromatography.The molecular weight of amidase was estimated to be 60.6×10³ by 12.5% SDS-PAGE. Its N-terminal sequence was ATIRPDDKAI. The optimum pH and temperature of the amidase for acrylamide were pH 7.5 and 35℃, respectively. The enzyme was unstable at a temperature over 50℃ and only 10.8% activity was retained after exposure to 60℃ for 30 min. Most of metal ions and EDTA had no significant effect on the enzyme activity, whereas Hg⁺，Ag⁺ and urea caused obvious inhibition.The K _m and V _max values of the amidase for acrylamide were 2.64 mmol·L^-1 and 0.6 μmol·min^-1·ml^-1, respectively.