Fig. 2.

Intracellular accumulation of UDP-N-acetylmuramyl pentapeptide in untreated and vancomycin-treated (A) and amphomycin-treated and MX-2401-treated (B) S. simulans 22 cells. The experiment was performed with 10× MIC of the respective antibiotic compounds for 45 min. Subsequently, cells were extracted with boiling water, and the intracellular nucleotide pool was analyzed by reverse-phase HPLC. The identity of UDP-MurNAc-pentapeptide was confirmed by MALDI-TOF mass spectrometry, yielding a molecular mass of 1,148.72 Da for the indicated peaks (arrows).