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Genetic and Biochemical Studies on Cell-Bound -Amylase in Bacillus subtilis Marburg

^a Division of Enzymology, The Institute of Applied Microbiology, The University of Tokyo, Bunkyo-ku, Tokyo, Japan

ABSTRACT

A small but significant amount of -amylase activity was detected in the cells of Bacillus subtilis Marburg. The cell-associated activity was almost constant regardless of the level of extracellular -amylase activity. The cell-bound amylase activity could be separated into three components, upon Sephadex G-75 chromatography, referred to as components A, B, and C. Component C showed the same properties as the extracellular -amylases so far examined. Component A had a molecular weight greater than 70,000, as judged from the elution position on Sephadex G-75, and became smaller upon treatment with trypsin but was still larger than that of component C. An -amylase mutant that lacked extracellular -amylase completely because of a mutation within the structural gene of the enzyme was found to lose all three cell-bound amylase components simultaneously. These data suggest strongly that the cell-bound amylase components are precursors of the extracellular -amylase and that the -amylase of this organism is produced under the direction of the same gene whether the enzyme is within or outside the cell.

¹ Present address: Biophysics Division, Cancer Research Institute, Kanazawa University, 13-1, Takara-machi, Kanazawa, Japan.