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.

Sequential mass spectrometry of saccharides: Identification of 2‐deoxy‐2‐aminohexose stereoisomers in glycoconjugates

“…ion beam contains a metastable excited state. Kr" (4p'4S)+Me(ls'S) 4 Kr't(4p''P,,,)+He' ('S) 11 7 c Kr" (4piJS)+He(l\'S) 4 Kr"(4p4'DZ)+He+ ('S) 10 5…”

Identification of carbohydrate and nucleic acid biomarkers in the pyrolysis electron ionization-high-resolution mass spectrum of Brucella neotomae

“…Monosaccharides have been characterized by electron ionization (EI) [5,6], field desorption (FD) [7][8][9], chemical ionization (CI) [5,6] and fast atom bombardment (FAB) [10] mass spectrometry. Application of desorption chemical ionization (DCI) to glycosides has also been described [11][12][13][14][15].…”

“…Biomarker m/z 115Of the peaks found in the m/z 115 cluster, only the peak at m/z 115.0641 (C5 H 9 O 2 N) was observed in the carbohydrate standard, N-acetylglucosamine (NAG). The precursor ions of m/z 115.0641 in the B. neotomae spectrum include m/z 143.0598 (C 6 H 9 O 3 N), m/z 185.0711 (C 8 H 11 O 4 N) and m/z 186.0788 (C 8 H 12 O 4 N).…”

Stereoisomer differentiation of 2-acetamido-2-deoxyhexose by mass spectrometric measurement of relative gas-phase alkali ion affinities

“…However it has been shown that EI-MS of permethylated iV-acetylhexosamines allows the localization of the acetamido group in the C-l, C-2, C-3, or C-4 positions. Moreover, Cl of Me3Si derivatives of some 2-IV-acetyl hexosamine stereoisomers using methane as reactant gas gives mass spectra in which it is the relative intensities of the fragment ions that allows their differentiation (5).…”