Extraction and identification by mass spectrometry of undecaprenyl diphosphate-MurNAc-pentapeptide-GlcNAc from Escherichia coli

Undecaprenyl diphosphate-MurNAc-pentapeptide-GlcNAc (lipid II) is extracted from Escherichia coli cells by utilizing its unusual pH-dependent solubility property in a Bligh-Dyer system, and identified by electrospray ionization mass spectrometry in conjunction with a novel N-15 mass shift analysis. The described approach will facilitate the structural characterization of lipid 11 variants from diverse bacteria, including antibiotic-resistant mutants, as well as the numerous minor uncharacterized lipids present in all biological systems. (C) 2005 Elsevier Inc. All rights reserved.