Autolytic Enzyme Associated with Cell Walls of Bacillus subtilis

Autolysis of cell walls of the highly transformable strain 168 of Bacillus subtilis is accompanied by the release of N-terminal L-alanine without a concomitant release of C-terminal amino acids, reducing groups, or phosphomonoester groups. These observations show that the enzyme is an N-acylmuramyl-L-alanine amidase. Autolysis follows first order kinetics, requires an energy of activation of 9.2 kcal per mole, and results in the hydrolysis of 87% of the amide bonds between muramic acid and L-alanine. Since the enzyme is most active during logarithmic growth of the population, it is suggested that its action coupled with a transpeptidase is involved in the expansion of the cell wall.