title: Identification of amino sugars from bacterial lipopolysaccharides by gas chromatography electron impact and chemical ionization mass spectrometry.
abstract: Amino sugars isolated from lipopolysaccharides of Brucella suis, Brucella abortus and Neisseria gonorrhoeae colony types 1 and 4 were identified using gas chromatography electron impact and chemical ionization mass spectrometry. Lipopolysaccharides were obtained by aqueous ether or aqueous phenol extraction. Isolated lipopolysaccharides were hydrolyzed in 1% acetic acid followed by hydrolysis of the polysaccharide moiety in 2 NHCl for 6 h at 100 degrees C. Amino sugars were first isolated by elution from Dowex 50 H+ and then N-acetylated, followed by trimethylsilylation. Trimethylsilyl ethers of 2-acetamido-2-deoxysugars; N-acetylglucosamine, N-acetylmannosamine, N-acetylgalactosamine, and a 2-acetamido-2.6-dideoxysugar, N-acetylquinovosamine, were identified by their fragmentation patterns. In the electron impact mode, N-acetylglucosamine and N-acetyl-galactosamine were distinguished from one another by comparing peak intensities at m/e 233 and 305. However, N-acetylglucosamine and N-acetylmannosamine could not be differentiated by electron impact mass spectrometry. In the chemical ionization mode, N-acetylglucosamine and N-acetylmannosamine both with base peaks at m/e 494, could be distinguished from N-acetylgalactosamine and N-acetylquinovosamine by their base peaks at m/e 420 and 332, respectively. N-Acetylglucosamine and N-acetylmannosamine were differentiated from one another by comparing peak intensities at m/e 330, 404, 420, and 510 [MH]+. This is the first report of chemical ionization mass spectrometry applied to the identification of amino sugars in bacterial lipopolysaccharides and shows that some 2-amino-2-deoxysugars can be differentiated by both electron impact and chemical ionization mass spectrometry.
mesh_terms: D000606:Amino Sugars / Q000302:isolation & purification*; D002002:Brucella / Q000032:analysis*; D002003:Brucella abortus / Q000032:analysis*; D004583:Electrons; D006595:Hexosamines / Q000302:isolation & purification; D007477:Ions; D008070:Lipopolysaccharides / Q000032:analysis / Q000302:isolation & purification*; D013058:Mass Spectrometry / Q000379:methods*; D009344:Neisseria gonorrhoeae / Q000032:analysis*
chemical_list: D000606:Amino Sugars; D006595:Hexosamines; D007477:Ions; D008070:Lipopolysaccharides