Structural investigation of the lipopolysaccharide core isolated from a virulent strain of Vibrio ordalii

Eur J Mass Spectrom (Chichester)

Cohen

Aneed

et al. 2004

The molecular structure of the mutant form of the lipopolysaccharide of Aeromonas salmonicida was determined to contain an O-4 phosphorylated and O-5 substituted Kdo reducing group, and is proposed as the following: [molecular structure: see text] It was established that during the cleavage of this LPS with 1% acetic acid, to release the core oligosaccharide from the Lipid A portion, we obtained a degraded core oligosaccharide which eliminated its phosphate group with extreme facility. The precise molecular structure of this dephosphorylated core was deduced by electrospray mass spectrometry and is proposed as the following:[molecular structure: see text] Low energy collision ESI-QqTOF-MS/MS analysis of the dephosphorylated core oligosaccharide confirmed the presence of the O-5 glycosylated 4,8- and 4,7-anhydro derivatives of the enolizable alpha-keto-acids. The CID tandem mass spectrometric analysis of the heterogeneous mixture of the permethylated core oligosaccharide established the unreported methylation reaction on the diastereomeric 4,8- and 4,7-anhydro alpha-keto-acids and the complete permethylation and addition reaction of the O-5 glycosylated open chain reducing end terminal D-arabino-3-en-2-ulonic acid. The stereo-specific fragmentation routes obtained during the tandem mass spectrometric analysis permitted the precise sequencing of this dephosphorylated rough core oligosaccharide of the mutant LPS of A. salmonicida.

Section: Resultsmentioning

confidence: 99%

Structural Reinvestigation of the Core Oligosaccharide of a Mutant Form of Aeromonas Salmonicida Lipopolysaccharide Containing an O-4 Phosphorylated and O-5 Substituted Kdo Reducing end Group Using Electrospray Quadrupole Time of Flight Tandem Mass Spectrometry

Eur J Mass Spectrom (Chichester)

Cohen

Aneed

et al. 2004

“…18 We have previously described the O-chain antigen and core oligosaccharide structures of a selection of the Vibrionaceae species. 19,20 These studies were directed toward the understanding of the role that LPS can play in the protection of fish against specific diseases. Also, part of these investigations were to determine whether various LPS fractions conjugated to proteins or encapsulated in liposomal carriers could be potentially used as protective vaccines.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the O-4 Phosphorylated and O-5 Substituted Kdo Reducing End Group and Sequencing of the Core Oligosaccharide of Aeromonas Salmonicida ssp Salmonicida Lipopolysaccharide Using Tandem Mass Spectrometry

Eur J Mass Spectrom (Chichester)

Aneed

Cohen

et al. 2004

The molecular structure of the wild strain of the lipopolysaccharide (LPS) core of Aeromonas salmonicida, ssp salmonicida has been sequenced using tandem mass spectrometry. The core oligosaccharide was determined to contain an O-4 phosphorylated and O-5 substituted Kdo reducing group and its structure is proposed as follows:After the core oligosaccharide of LPS was released from the lipid A portion by conventional treatment with 1% acetic acid, we demonstrated the existence of a homogeneous mixture composed mainly of the native core oligosaccharide containing the Kdo with its O-4 phosphate group intact and a degraded core oligosaccharide mixture which eliminated the O-4 phosphate group with extreme ease. The precise molecular structure and glycone sequence of the homogeneous mixture of phosphorylated and dephosphorylated core oligosaccharides was determined by electrospray ionization mass spectrometry and tandem mass spectrometric (MS/MS) analysis. Collision-induced dissociation MS/MS of the homogeneous mixture of permethylated core oligosaccharides afforded a series of diagnostic product ions which confirmed the established sequence of the glycones to be determined. Matrix-assisted laser desorption/ionization MS/MS reconfirmed the molecular structure of the dephosphorylated homogeneous permethylated mixture of the core oligosaccharides containing the diastereomeric 4,8-and 4,7-anhydro-α-keto acids.Keywords: structural investigation, Aeromonas salmonicida ssp salmonicida, lipopolysaccharide, native phosphorylated core oligosaccharide, degraded dephosphorylated core oligosaccharide, electrospray and matrix-assisted laser desorption/ionization, mass spectrometry and tandem mass spectrometry L-α-D-Hepp

“…Identification of 3-deoXY-D-manno-2-octulosonic acid (Kdo) was achieved by GC-EI-MS and it was found that this core oligosaccharide contained only one residue ofKdo which connected the native oligosaccharide to the Lipid A [9]. We have suggested that the reducing Kdo was prone to fonn a lactone [15], and it was established that the single Kdo residue of this family of bacteria, which glycosidically attaches the core oligosaccharide to the non-reducing glucosamine unit of Lipid A, was in the furanose fonn [16,17] and linked through C-6.…”

Section: Resultsmentioning

confidence: 99%

Analysis of the Core Oligosaccharide of Aeromonas hydrophila (Chemotype III) Lipopolysaccharide Using Fast Atom Bombardment, Electrospray and Low Energy Tandem Mass Spectrometry

Journal of Spectroscopy

Gentip

Shaw

1994

Fast-atom bombardment mass spectrometry (FAB-MS) was employed for the structural analysis of the core oligosaccharide ofAeromonas hydrophila(Chemotype III) lipopolysaccharide. Positive ion FAB-MS of the underivatized core oligosaccharide gave the protonated molecular ion, confrrming the correct composition in terms of hexoses, heptoses and Kdo which was present as a bicyclic furanosidic lactone. Negative ion FAB-MS gave the deprotonated molecular ion and fragment ions which were derived from more than two cleavage events with charge retention at the reducing and non-reducing terminals. Positive ion F AB-MS of the permethylated core oligosaccharide afforded fragment ions consistent with the defined sequence and branching patterns of the sugar constituents. The electrospray mass spectrum (ESMS) in the positive ion mode of the underivatized core oligosaccharide afforded the protonated molecular ion in the singly and doubly charged forms. Low energy collision-activated dissociation tandem mass spectrometry (CAD MS/MS) analysis of the protonated molecular ion [M+2H]+2provided additional structural data. ESMS of the permethylated and N-acetylated permethylated core oligosaccharides provided useful structural indices and afforded a characteristic pattern for fragmentions resulting from the opening of the methylated bicyclic Kdo furanosidic 1,7- lactone, which was similar to that obtained in the corresponding FAB-MS.