Analysis by surface plasmon resonance of the influence of valence on the ligand binding affinity and kinetics of an anti-carbohydrate antibody

The kinetics of ligand binding by Se155-4, an antibody specific for the Salmonella serogroup B O-polysaccharide, were studied by surface plasmon resonance. Because trace amounts of oligomers in Fab and single-chain antibody variable domain (scFv) preparations resulted in biphasic binding profiles that were difficult to analyze, all kinetic measurements were performed on purified monomeric fragments and, for certain mutant scFv, dimeric forms. Results obtained with monomeric forms indicated that the relatively low affinity of the antibody was due to rapid dissociation (koff approximately 0.25 s-1). Dimeric forms generally showed off-rates that were approximately 20-fold slower and a 5-fold increase in association rate constants to approximately 2 x 10(5) M-1 s-1. Although the association phases for scFv dimers showed good curve fitting to a one component interaction model, the dissociation phases were biphasic, presumably because the availability and accessibility of sites on the antigen always leads to some monovalent attachment. The fast off-rate for dimers was the same as the monomer off-rate. Se155-4 IgG off-rates were very similar to those observed for scFv dimer, whereas the onrate was the same as that obtained with Fab and scFv monomer.

[Structure of a new lysine-containing O-specific polysaccharide from Proteus mirabilis O26]

The composition and structure of the O-specific polysaccharide chain of the bacterium Proteus mirabilis O26 lipopolysaccharide have been studied using one- and two-dimensional 1H- and 13C-NMR spectroscopy, including homonuclear correlation spectroscopy (COSY), H-detected 1H,13C heteronuclear multi-quantum coherence and rotating-frame nuclear Overhauser effect spectroscopy. It has been found that the polysaccharide is acidic due to the presence of D-galacturonic acid (D-GalA) residues, part of which are O-acetylated, while the other part form an amide with the alpha-amino group of L-lysine and is built up of tetrasaccharide repeating units having the following structure: [formula: see text] The P. mirabilis O26 polysaccharide is structurally similar to the O-specific polysaccharide of P. mirabilis O28 studied earlier by us and containing amides of D-galacturonic acid with L-lysine and L-serine.

Structural characterization of the O-antigenic polysaccharide of Escherichia coli serotype 017 lipopolysaccharide

The structure of the O-polysaccharide component of the lipopolysaccharide produced by Escherichia coli 017 (ATCC 23512) was determined by the use of methylation, periodate oxidation, one- and two-dimensional nuclear magnetic resonance spectroscopy, and mass spectrometric methods. The O-polysaccharide was found to be a high molecular weight polymer of repeating branched pentasaccharide units composed of D-mannose, D-glucose, and 2-acetamido-2-deoxy-D-glucose residues (3:1:1) and had the structure (formula: see text).

Structure of the O-specific polysaccharide chain of Shigella boydii type 5 lipopolysaccharide: a repeated study

An acidic, partially O-acetylated O-specific polysaccharide was obtained by mild acid degradation of Shigella boydii type 5 lipopolysaccharide and studied by 1H and 13C NMR spectroscopy, including 2D COSY, 13C-1H heteronuclear COSY, 1D NOE, and 2D ROESY experiments, and chemical methods (sugar and methylation analysis, O-deacetylation, carboxyl reduction, solvolysis with anhydrous HF, partial acid hydrolysis. Smith degradation). It was concluded that the polysaccharide has a hexasaccharide repeating unit of the following structure: [Formula: See Text] with the degree of O-acetylation varying over 30-50%. The established structure differs from that proposed recently for the O-specific polysaccharide of the same S. boydii serotype [M.J. Albert et al., Carbohydr. Res., 265 (1994) 121-127].

Synthesis of the methyl alpha-glycoside of a trisaccharide mimicking the terminus of the O antigen of Vibrio cholerae O:1, serotype Inaba

Coupling of methyl 4-amino-4,6-dideoxy-2-O-4-methoxybenzyl-alpha-D-mannopyranoside, obtained from the corresponding 4-azido derivative by treatment with H2S, with 3-deoxy-L-glycero-tetronolactone gave the crystalline methyl 4-(3-deoxy-L-glycero-tetronamido)-4,6-dideoxy-2-O-4-methoxybenzyl- alpha-D- mannopyranoside (7). Subsequent acetylation of 7, followed by O-demethoxybenzylation of the 8 formed gave the crystalline methyl 3-O-acetyl-4,6-dideoxy-4-(2,4-di-O-acetyl-3-deoxy-L-glycero-tetronami do)-alpha- D-mannopyranoside (9), which was used as the key intermediate in the construction of the title trisaccharide. To make a glycosyl donor allowing the extension of the oligosaccharide chain at O-2, compound 9 was converted, via conventional transformations, into 3-O-acetyl-2-O-bromoacetyl-4,6-dideoxy-4-(2,4-di-O-acetyl-3-deoxy-L-glyc ero- tetronamido)-alpha-D-mannopyranosyl chloride (12). Condensation of 12 with 9 afforded the disaccharide 20 having a selectively removable protecting group at O-2(2). The latter was O-debromoacetylated, and the disaccharide nucleophile thus obtained was treated with 2,3-di-O-acetyl-4,6-dideoxy-4-(2,4-di-O-acetyl-3-deoxy-L-glycero-tetr onamido)- alpha-D-mannopyranosyl chloride to give, after O-deacetylation, the target, title trisaccharide. The constituent monosaccharide of the O-specific polysaccharide antigen of Vibrio cholerae serotype Inaba, 4-(3-deoxy-L-glycero-tetronamido)-4,6-dideoxy-D-mannopyranose (18), was obtained from the peracetate of its methyl alpha-glycoside by acetolysis, followed by O-deacetylation. The amorphous compound 18 was characterized by 1H and 13C NMR spectroscopy and through its crystalline alpha-per-O-acetyl derivative.

Structures of decasaccharide and tridecasaccharide tetraphosphates isolated by strong alkaline degradation of O-deacylated lipopolysaccharide of Pseudomonas fluorescens strain ATCC 49271

Mild hydrazinolysis of Pseudomonas fluorescens strain ATCC 49271 lipopolysaccharide (LPS) followed by strong alkaline degradation and purification by anion-exchange HPLC resulted in two phosphorylated oligosaccharides (1 and 2). On the basis of compositional analysis and 1H, 13C, and 31P NMR spectroscopy, including 2D correlation spectroscopy (COSY), 2D rotating frame NOE spectroscopy (ROESY), and 2D inverse mode H-detected heteronuclear 1H-13C and 1H-31P correlation spectroscopy, the following two structures (1 and 2) could be identified [formula: see text] where Hep is L-glycero-D-manno-heptose, Kdo is 3-deoxy-D-manno-octulosonic acid, Non is 5,7-diamino-3,5,7,9-tetradeoxy-D-glycero-L-galacto-nonulosonic acid, and P is phosphate. Decasaccharide 1 and tridecasaccharide 2 represent an incomplete core and the complete core carrying one O-antigen repeating unit, respectively. Both are attached to the lipid A backbone but, due to their degradation protocol, they lack N- and O-acyl substituents, including N- and O-acetyl groups, the 5-N-acetimidoyl group of Non, the 2-N-alanyl group of GalN, and the 7-O-carbamoyl group of Hep as well as diphosphate, triphosphate, and, probably, some of the monophosphate groups that are present in the intact core oligosaccharide.

[Structure and properties of the common polysaccharide antigen of Pseudomonas aeruginosa bacteria (review)]

The review is devoted to a surface carbohydrate antigen of the bacterium Pseudomonas aeruginosa which is common for the majority of the species and has a lipopolysaccharide nature. The occurrence, detection, isolation, structure, expression on the cell surface, interaction with antibodies, an antibiotic and a bacteriophage as well as the immunotherapeutic potential of the common polysaccharide antigen are discussed.

NMR investigation of the 6-deoxy-L-talose-containing O45, O45-related (O45rel), and O66 polysaccharides of Escherichia coli

The structures of the 6-deoxytalose-containing O-specific polysaccharides from the O45 antigen, an O45-related antigen (O45rel), and the O66 antigen (lipopolysaccharides, LPSs) of Escherichia coli were elucidated by chemical characterization and by one- and two-dimensional 1H and 13C NMR spectroscopy. The O45 and O45-related polysaccharides have the following general structure: [formula: see text] For the O45 antigen, X is alpha-D-FucpNAc and for the O45-related antigen, X is beta-D-GlcpNAc. The structure of the O66 polysaccharide is [formula: see text]

Structure of the Hafnia alvei strain PCM 1188 O-specific polysaccharide

The lipopolysaccharide was extracted from cells of Hafnia alvei PCM 1188 strain and, after mild acid hydrolysis, the O-specific polysaccharide isolated and characterized. On the basis of sugar and methylation analysis, FAB mass spectrometry and NMR spectroscopy of the polysaccharide and oligosaccharides obtained after Smith degradation, or solvolysis with anhydrous hydrogen fluoride, the repeating unit of the O-specific polysaccharide was shown to be the pentasaccharide: [formula: see text]

Structure of the O-specific side chain of the Escherichia coli O128 lipopolysaccharide

The O-specific polysaccharide isolated from Escherichia coli O128 lipopolysaccharide contains D-galactose, L-fucose, and 2-acetamido-2-deoxy-D-galactose in the molar ratios 2:1:2. The primary structure of the O-specific polysaccharide from E. coli was established by compositional analysis, methylation analysis, together with 1H and 13C NMR spectroscopy including two-dimensional shift-correlated and one-dimensional NOE spectroscopy. The polysaccharide moiety was found to consist of a tetrasaccharide backbone containing D-galactose and 2-acetamido-2-deoxy-D-galactose, with L-fucose as a side chain in a branched pentasaccharide repeating unit having the following structure: [formula: see text]

Structural studies of the putative O-specific polysaccharide of Acinetobacter baumannii O2 containing 3,6-dideoxy-3-N-(D-3-hydroxybutyryl)amino-D-galactose

A polysaccharide containing D-galactose, 2-deoxy-2-N-acetylamino-D-galactose and 3,6-dideoxy-3-N-(D-3-hydroxybutyryl)amino-D-galactose, probably corresponding to the lipopolysaccharide side chain, was obtained from an aqueous phenol extract of isolated cell walls from Acinetobacter baumannii strain O2. By means of NMR studies and chemical degradations, the repeating unit of the polymer was identified as a branched hexasaccharide of the structure shown, where Fuc3N represents 3-amino-3,6-dideoxygalactose and R represents D-3-hydroxybutyryl. Serological tests indicated that the polymer corresponded to the O2 antigen.

Structural elucidation of the O-antigenic polysaccharide from Escherichia coli O44:H18

The O-antigen polysaccharide of the lipopolysaccharide from the enteroaggregative Escherichia coli O44:H18 has been investigated. Sugar and methylation analysis, 1H- and 13C-NMR spectroscopy revealed that the polysaccharide is composed of pentasaccharide repeating units. The sequence of sugar residues was determined by use of two-dimensional nuclear Overhauser effect spectroscopy and heteronuclear multiple bond correlation experiments. The structure of the repeating unit of the O-antigen from Escherichia coli O44:H18 is as follows. [formula: see text]

Structural analysis of the O-antigen of the lipopolysaccharide of Rhizobium tropici CIAT899

The structure of the O-antigen chain of the lipopolysaccharide isolated from Rhizobium tropici CIAT899, by the phenol-water procedure, and recovered from the phenol layer, has been investigated by hydrolysis, methylation analysis and 1D and 2D 1H and 13C NMR spectroscopy of the complete polysaccharide and of oligosaccharides obtained by partial hydrolysis. The O-antigen has the repeating unit [formula: see text]

Role of O-antigen variation in the immune response

The O antigen is an extremely variable surface polysaccharide of Gram-negative bacteria. This variation is thought to allow the various clones of a species each to present a surface that offers a selective advantage in the niche occupied by that clone. The interactions between O antigen and the immune system are central to determining the selective advantage of each clone.

Role of LPS length in clearance rate of bacteria from the bloodstream in mice

Strains of Pseudomonas aeruginosa isolated from patients with cystic fibrosis (CF) never spread systemically. This may be due to serum sensitivity since these strains are very sensitive to complement-mediated bactericidal activity. A serum-resistant mutant, P. aeruginosa TUM3 HSR, was obtained from serum-sensitive strain TUM3 from a CF patient in order to clarify the mechanism of failure of systemic spread. LPS profiles on silver-stained gels and immunological analysis revealed that a long O-polysaccharide side chain was overproduced on the LPS molecules of TUM3 HSR as compared with the LPS of TUM3. The clearance rate from the bloodstream in mice was compared in the two strains. The number of TUM3 bacteria in 1 ml of blood, 10 min after injection into the tail vein, significantly decreased from 1.7 x 10(8) to 3.7 x 10(5) c.f.u. ml-1. In contrast, TUM3 HSR was not eliminated during the same period (decrease from 1.9 x 10(8) to 3.4 x 10(7) c.f.u. ml-1). Interestingly, these isogenic strains were not killed by 40% murine serum, probably reflecting immaturity of the complement-mediated killing system in mice. These results pointed to a correlation between LPS structure and blood clearance rate in mice. This was confirmed by examining blood clearance kinetics using the smooth-LPS strain Salmonella typhimurium LT2 and LPS-deficient mutants derived from it. S. typhimurium LT2 resisted blood clearance while the LPS-deficient mutants were cleared rapidly. None of the S. typhimurium strains were killed by murine serum. The number of P. aeruginosa TUM3 and S. typhimurium LPS-deficient mutants trapped in the liver following injection into the peripheral circulation was greater than that of their counterparts.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthesis and crystal structure of methyl 4-6-dideoxy-4-(3-deoxy-L- glycero-tetronamido)-2-O-methyl-alpha-D-mannopyranoside, the methyl alpha-glycoside of the terminal unit, and presumed antigenic determinant, of the O-specific polysaccharide of Vibrio cholerae O:1, serotype Ogawa

Methyl 4-azido-4,6-dideoxy-3-O-benzyl-alpha-D-mannopyranoside and its analogous 3-O-(4-methoxybenzyl) derivative were methylated and the 2-O-methyl derivatives formed were converted into methyl 4-amino-4,6-dideoxy-2-O-methyl-alpha-D- mannopyranoside [sequence: see text]. Reaction of the latter with 3-deoxy-L-glycero-tetronolactone gave the methyl glycoside of 4,6-dideoxy-4-(3-deoxy-L-glycero- tetronamido)-2-methyl-alpha-D-mannopyranose [sequence: see text], the monosaccharide that is reported to be the terminal moiety of the O-specific polysaccharide of Vibrio cholerae O:1, serotype Ogawa. The unit cell packing of the compound, which crystallized as a monohydrate, differs from that of the previously described crystalline compound lacking the 2-O-methyl group. The unmethylated sugar is the terminal moiety of the O-specific polysaccharide of Vibrio cholerae O:1, serotype Inaba. The crystal structure of methyl 4,6-dideoxy-2-O- methyl-4-trifluoroacetamido-alpha-D-mannopyranoside [sequence: see text] is also described.

Synthesis of specifically deoxygenated disaccharide derivatives of the Shigella dysenteriae type 1 O-antigen

The synthesis of methyl O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-D-galactopyranosides specifically deoxygenated at position 2 (31), or 4 (21) of the rhamnopyranosyl residue was accomplished using methyl 3,4,6-tri-O-benzoyl-alpha-D-galactopyranoside (18) as the glycosyl acceptor. Phenyl thionocarbonate activation of the penta-O-benzoylated disaccharide precursor followed by Barton reduction and Zemplén transesterification gave 31, while 21 was obtained via condensation of the deoxygenated monosaccharide donor with 18, and subsequent debenzoylation of the product.

The structure and serological specificity of Proteus mirabilis O43 O antigen

On the basis of sugar analysis and NMR spectroscopy, including selective spin-decoupling, one-dimensional NOE, two-dimensional homonuclear and 13C,1H-heteronuclear correlation spectroscopy, the following structure of the acidic O-specific polysaccharide of Proteus mirabilis O43 was established: -->4)-alpha-D-GalpA-(1-->3)-alpha-D-GalpA-(1-->3)-alpha-D-Gl cpNAc-(1-->4)-alpha - D-Glcp-(1-->, where GalA is galacturonic acid and Galp is galactopyranose. No serological cross-reactivity was observed between lipopolysaccharides of P. mirabilis O43 and other studied Proteus strains, except for P. mirabilis O10. The O-specific polysaccharide of P. mirabilis O43 was serologically active in precipitation and inhibition tests but the activity was lost after periodate oxidation. These data suggest that the O43 specificity is determined by a wide epitope with the immunodominant role of 4-substituted D-Glc or/and D-GalA, which are destroyed by periodate oxidation.

Structures of the O-specific polysaccharide chains of Pectinatus cerevisiiphilus and Pectinatus frisingensis lipopolysaccharides

Mild acid hydrolysis of the smooth-type lipopolysaccharide (LPS) of Pectinatus frisingensis afforded no polysaccharide but monomeric 6-deoxy-L-altrose (L-6dAlt) which was identified by anion-exchange chromatography in borate buffer, GLC/MS, 1H-NMR spectroscopy, and optical rotation. LPS was degraded with alkali under reductive conditions to give a completely O-deacylated polysaccharide, which was studied by methylation analysis, 1H-NMR and 13C-NMR spectroscopy, including sequential, selective spin-decoupling, two-dimensional correlation spectroscopy (COSY), COSY with relayed coherence transfer, two-dimensional heteronuclear 13C, 1H-COSY, one-dimensional NOE and two-dimensional rotating-frame NOE spectroscopy. It was found that the O-specific polysaccharide chain of P. frisingensis LPS is a homopolymer of 6-deoxy-L-altrofuranose built up of tetrasaccharide-repeating units having the following structure: [sequence: see text] Similarly, mild acid degradation of smooth-type LPS of Pectinatus cerevisiiphilus resulted in depolymerisation of the polysaccharide chain to give a disaccharide consisting of D-glucose and D-fucose. Study of the disaccharide by methylation analysis and alkali-degraded LPS by one-dimensional and two-dimensional 1H-NMR and 13C-NMR spectroscopy showed that the O-specific polysaccharide of P. cerevisiiphilus has the following structure: -->2)-beta-D-Fucf-(1-->2)-alpha-D-Glcp-(1-->.

Structure of the O-specific polysaccharide of Hafnia alvei 1204 containing 3,6-dideoxy-3-formamido-D-glucose

The O-specific polysaccharide of Hafnia alvei strain 1204 has a hexasaccharide repeating unit containing D-mannose, D-glucuronic acid, 2-acetamido-2-deoxy-D-glucose, 2-acetamido-2-deoxy-D-galactose, and 3,6-dideoxy-3-formamido-D-glucose (Qui3NFo) in the ratios 2:1:1:1:1 as well as O-acetyl groups. On the basis of methylation analysis of the intact, carboxyl-reduced, and Smith-degraded polysaccharide as well as 1D and 2D NMR spectroscopy, including 1D total correlation spectroscopy, 1D NOE spectroscopy, 2D homonuclear shift-correlated spectroscopy (COSY), and 13C,1H heteronuclear COSY, the following structure of the O-deacetylated polysaccharide was established: -->3)-alpha-D-Manp-(1-->2)-alpha-D-Manp-(1-->3)-beta-D-GlcpN Ac-(1--> -->2)-beta-D-Quip3NFo-(1-->3)-alpha-D-GalpNAc-(1-->4)-alpha-D-G lcpA-(1--> Location of the N-formyl group, occurring as two stereoisomers in the ratio approximately 3:1, was determined by an NOE on H-3 Qui3N arising on pre-irradiation of HCO of the minor (E) isomer. The O-acetyl groups are attached in nonstoichiometric amounts at position 3 of GlcA and position 6 of a mannose residue or GlcNAc.

Characterization of a lipopolysaccharide O antigen containing two different trisaccharide repeating units from Burkholderia cepacia serotype E (O2)

The O antigen of the lipopolysaccharide of Burkholderia cepacia serotype E (O2) was shown by a combination of methylation analysis, partial hydrolysis, NMR, and mass spectrometric methods to be a high molecular weight polysaccharide composed of two different trisaccharide repeating units in the ratio 2:1. The major trisaccharide component is composed of two alpha-D-mannopyranosyl and one beta-D-galactopyranosyl residues with the structure, [-->2)-alpha-D-Man p-(1-->2)-alpha-D-Man p-(1-->4)-beta-D-Gal p-(1-->]n The minor trisaccharide component is a D-mannan composed of two alpha- and one beta-D-mannopyranosyl residues with the structure, [-->2)-alpha-D-Man p-(1-->2)-alpha-D-Man p-(1-->3)-beta-D-Man p-(1-->]n