Fig. 3.

Determination of O-acetylated muropeptides by HPLC analysis. The cell walls of all three strains were isolated and enzymatically digested into monomeric muropeptides by mutanolysin and lysostaphin. The O-acetylated and nonacetylated muropeptides were separated by HPLC, and the content of the two most prevalent peak groups was determined by MS. The peak group at retention time 60 to 75 min contains nonacetylated muropeptides, while the muropeptides at the peak retention times of 75 to 85 min are O-acetylated.