Abstract: After amonanium sulfate precipitation followed by ion-exchange chromatography on CM-Sepharose column and Superdex-200 gel-filtration, ribonuclease from Bacillus megaterium was purified to electrophoretic homogeneity. Some of its enzymological properties were then explored. The results showed that the enzyme was 606.67-fold purified with specific activity of 54272.27 U/mg and recovery rate of 11.37%. The molecular weight was 33.3 kD. Optimum activity of the enzyme was achieved at 52.5 ℃ and pH 8.5. The enzyme displayed good stability at 20—40 ℃ and pH 6.0—7.0. The activity of this enzyme was inhibited by Fe2+, Cu2+, SDS, ascorbic acid and oxalic acid.

Key words: Bacillus megaterium, ribonuclease, isolation and purification, characterization