Muramic Acid Phosphate as a Component of the Mucopeptide of Gram-positive Bacteria

In earlier work, a phosphorylated derivative of muramic acid was detected upon amino acid analysis of acid hydrolysates of pneumococcal C polysaccharide. This substance has now been identified as muramic acid 6-phosphate by periodate oxidation, followed by the identification of glycolaldehyde phosphate in the oxidation mixture. Muramic acid phosphate has been found in hydrolysates of the cell walls obtained from all of the eight other species of gram-positive bacteria examined. It accounts for 7 to 39% of the total muramic acid present. It cannot be found in the membrane or in the cytoplasm of Streptococcus, nor can it be detected in the two gram-negative species analyzed. In two organisms studied, Dipiococcus pneumoniae and Streptococcus, evidence was obtained that the muramic acid phosphate isolated was originally part of a phosphodiester bond which cross-linked the mucopeptide polymer with the specific polysaccharide of the cell wall.