Structural variations in bacterial cell wall peptidoglycans studied with Streptomyces F1 endo-N-acetylmuramidase

An improved procedure for the purification of the Streptomyces FI [beta]-l,4 endo-N-acetylmuramidase is described. FI enzymes digests cell walls from bacteria of the most important grampositive genera. Its mechanism of action upon cell walls of Staphylococcus aureus, Micrococcus roseus, and Micrococcus lysodeikticus has been studied. To all appearances, the affinity of the F1 enzyme for the glycosidic linkages of N-acetylmuramic add in the polysaccharide chains is greatly enhanced by the peptide substitution of these residues. From an integration of the properties of the FI enzyme digests of various cell walls, it appears that tight network peptidoglycans, typified by a high degree of cross-linkings of the polysaccharide chains through peptide unites, as they occur in cell wals of S. aureus and M. roseus, are not encountered in many cell walls from gram-positive bacteria.