Varying electrophoretic mobility of an esterase caused by a factor in extracts of Bacillus stearothermophilus cells
The esterase pattern on polyacrylamide gel of extracts from Bacillus stearothermophilus grown at different temperatures from 45 to 71 °C was examined by slab gel electrophoresis. The esterase pattern showed the presence of eight esterase bands in the extracts from bacterial cells grown at 60 °C. These bands could be divided into two groups. One group included seven esterase bands which showed constant electrophoretic mobilities at different growth temperatures. The other group included one esterase band, Est-b, which showed different mobilities depending on growth temperature. A factor, which increased the mobility of Est-b, could be separated from cell extracts by gel filtration. The mobility of partially purified Est-b was regulated by addition of various amounts of the factor. At 70 °C, the thermostability of partially purified Est-b was increased by adding the factor; this was accompanied by competitive inhibition of the enzyme activity.