Purification and some properties of β-galactosidase of Bacillus subtilis

Abstract

1. 1. β-Galactosidase (β--galactoside galactohydrolase, EC 3.2.1.23) was isolated from Bacillus subtilis and partially purified.

2. 2. When the measurements were made at saturating or nearly saturating concentrations of substrate there was a linear relationship between the quantity of enzyme and the amount of product formed, and a linear formation of product with time. The enzymic activity was not influenced by ions.

3. 3. The optimum pH for hydrolytic activity was 6.5.

4. 4. The optimum temperature for hydrolysis was 50°. The enzyme was relatively heat-stable. The enzyme was not inactivated during 1 h at 50°. At 55° the inactivation was 15% after 30 min of exposure.

5. 5. The affinity constant for lactose was 7.1 · 10−1. The constants for the common substrates of the β-galactosidase of B. subtilis were different from those of the Escherichia coli enzyme.