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.