Characterization of the N-acetylmuramic acid L-alanine amidase from Bacillus subtilis.

The N-acetylmuramic acid L-alanine amidase from Bacillus subtilis W-23 has been purified to apparent homogeneity. The enzyme is a monomer of molecular weight 51,000, which binds extremely tightly to homologous cell walls but not to heterologous cell walls, even of the closely related strain B. subtilis ATCC 6051. This difference in binding is only in part due to differences in teichoic acid between these two strains and to a large extent appears to represent differences in the arrangement of the peptidoglycan. A comparison of the amidase from B. subtilis W-23 and the enzyme previously purified from B. subtilis ATCC 6051 (Herbold and Glaser, 1975) shows that the two proteins, which cleave the same bond and are of the same size, do not cross-react immunologically and that the two enzymes are, therefore, not closely related in structure.