On a Lea Substance-Decomposing Enzyme. I

Abstract

1. A strain of Bacillus cereus, which produced Le^a-decomposing enzyme, was isolated from the soil. This enzyme, when applied to Le (a+b-) red cells or water-soluble Le^a substance, decomposed it to abolish Le^a activity, and enhanced its cross-reactivity with anti-pneumococci Type XIV chicken serum. In addition to this enzyme, the strain produced A-decomposing enzyme. By means of DEAE cellulose column chromatography, Le^a-decomposing enzyme could be separated from A-decomposing enzyme. These enzymatic activities were found in a fraction that precipitated at 30-60% ammonium sulphate saturation of autolysate of the strain. Their optimal pH ranged from 6.8 to 7.2, and their optimal temperature ranged from 30° to 37°C. Treatment at 70°C for 5 minutes inactivated them. 2. The actions of these enzyme preparations were slightly inhibited by copper sulphate, mercuric chloride and strontium nitrate. The action of the Le^a-decomposing enzyme was also inhibited strongly by such sugars as L-fucose, D-galactose and lactose, and weakly by β-ethyl-N-acetyl-D-glucosamine and D-glucosamine, and action of the A-decomposing enzyme was inhibited strongly by N-acetyl-D-galactosamine, and weakly by D-galactosamine.