RESUMO
The crude preparation of Bacillus cereus beta-lactamase was fractionated by ammonium sulphate and purified [305.6 fold] by chromatography on CM-sephadex C50 and DEAE-sephadex A50. The purified enzyme had specific activity of 109.90 units /mg protein with a yield of 49.69%. The enzyme was found to be homogenous when electrophoresed by polyacrylamide gel in both absence and presence of sodium dodecyle sulphate since it showed a single distinctive band. SDS-PAGE analysis showed that the purified enzyme had a relative electrophoretic mobility of 0.86 and molecular weight of 23,400. The enzyme was found to be rich in glyciny, glutamic acid and serine, However, it contained low amount of methionine. The apparent Km and Vmax values of the purified enzyme were 128.20 [micro Mole and 76 micro Mole/mg protein /ml /min respectively, Maximum beta-lactamase activity was obsrved when incubated with the substrate at pH 8 for 15 min. at 30 °C