Ladislas Szabó

Do endotoxins devoid of 3-deoxy-D-manno-2-octulosonic acid exist?

After treatment with aqueous, 50% hydrofluoric acid, a well-known dephosphorylating agent, the presence of 3-deoxy-D-manno-2-octulosonic acid (KDO), an essential and characteristic constituent of endotoxins, can be readily demonstrated in reportedly KDO-deficient bacterial lipopolysaccharides.

Structure of a hexasaccharide proximal to the hydrophobic region of lipopolysaccharides present inBordetella pertussis endotoxin preparations

A branched-chain hexasaccharide containing 3-deoxy-D-manno-oct-2-ulosonic acid was released by detergent-promoted hydrolysis from Bordetella pertussis endotoxin preparations that were first dephosphorylated with aqueous HF and then treated with nitrous acid. Its structure (2) [Formula: See text] was determined by chemical and physical methods. This hexasaccharide is present in all four lipopolysaccharides that make up the B. pertussis strain 1414 (phase 1) endotoxin preparations analysed, and is situated near to the hydrophobic domains. An analogous structure reported previously (ref 7) is erroneous and should be disregarded.

Phosphorylated sugars. Part 27. Synthesis and reactions, in acid medium, of 5-O-substituted methyl 3-deoxy-α-D-manno-oct-2-ulopyranosidonic acid 4-phosphates

Synthesis of the α-methyl glycosides of 5-O-methyl-, 5-O-benzyl-8-O-methyl-, and 5,7,8-tri-O-methyl-3-deoxy-D-manno-oct-2-ulosonic acid 4-phosphates are described. The corresponding ‘reducing’ glycose, formed upon hydrolysis at pH 4 and 100 °C, immediately eliminates the phosphate group. The olefinic acids thus produced from 5-O-methyl-, and from 5-O-benzyl-8-O-methyl 4-phosphates are not stable under these conditions: they are transformed into 4,7- and 4,8 -anhydro-derivatives which have no ethylenic protons and show negligible absorption in the region 220–300 nm. The olefinic acid produced from the 5,7,8-tri-O-methyl derivative is unable to form such an anhydro-derivative: two ethylenic protons are present in its 1H NMR spectrum and, like other conjugated olefinic α-keto acids, it has a strong UV absorption band (λmax 235 nm, Iµ 8000).

O-demethylation of Per-O-methyl Derivatives of 2-amino 2-deoxyhexitols During Acid Hydrolysis and Acetolysis

Abstract Under conditions of acid hydrolysis, acetolysis, and methanolysis, 2-acet-amido-2-deoxy-, and 2-deoxy-1,3,4,5,6-penta- O -methyl-2-( N -methylacetamido)- d glucitol and - d -galactitol undergo O -demethylation, the N -methyl group being preserved. Upon acetylation, mainly 2-acetamido-I- O -acetyl-2-deoxy-, and 1- O -acetyl-2-deoxy-3,4,5,6-tetra- O -methyl-2-( N -methylacetamido)hexitol derivatives are formed. The previously postulated 2-( N -acetylacetamido)-2-deoxy-1,3,4,5,6-penta- O -methylhexitol derivatives were not detected.

Identification of 2-amino-6-O-(2-amino-2-deoxy-β-d-glucopyranosyl)-2-deoxy-d-glucose as a major constituent of the hydrophobic region of the Bordetella pertussis endotoxin

Abstract 2-Amino-6- O -(2-amino-2-deoxy-β- d -glucopyranosyl)-2-deoxy- d -glucose substituted on the amino group of the reducing 2-amino-2-deoxy- d -glucose unit by a 3-hydroxytetradecanoyl group was shown to be a major constituent of the “Lipid A” fragment obtained by acid hydrolysis of the Bordetella pertussis endotoxin.

Loss of O-methyl groups from methylated 2-amino-2-deoxy-D-glucitol and -D-galactitol derivatives under acidic conditions used during the analysis of glycoproteins

Abstract In the acetolysis/hydrolysis procedure (1), usually employed for the cleavage of permethylated oligosaccharides isolated from glycoproteins, O-demethylation of C-1 of the substituted, terminal hexosaminitol derivative occurs. Upon acetylation of the hydrolysate this yields a 1-O-acetyl-2-(N-methylacetamido)-2-deoxy-hexitol derivative and not, as suggested (2),a 2-acetylacetamido-2-deoxy-hexitol derivative.

The synthesis of 3-deoxy-4-O-methyl-D-arabino-2-heptulosonic acid and its behaviour in the warren reaction

Abstract 3-Deoxy-4- O -methyl- D - arabino -2-heptulosonic acid was synthesized in six steps starting from 2-deoxy- D - arabino -hexose. Treatment with periodate-thiobarbiturate (Warren reaction) gave a positive reaction with a molar absorption coefficient of 3700 to 5000 depending on the conditions of the periodate oxidation. It is suggested that the Warren reaction, which is eminently suitable for the detection of 3-deoxy-aldulosonic acids, should not be used for the quantitative estimation of 3-deoxy-2-aldulosonic acids of undetermined substitution pattern.

Synthesis of 1,5-lactones of 3-deoxy-d-manno-2-octulopyranosonic acid (KDO)

Abstract An unambiguous synthesis of methyl 3-deoxy-α- d - manno -2-octulopyranosidono-1,5-lactone from methyl (methyl 3-deoxy-α- d - manno -octulopyranosid)onate via the 7,8- O -isopropylidene derivative is described. Treatment of the 4,5-stannylene derivative of this acetal with benzyl bromide gave the 1,5-lactone from which the protecting groups were removed. The acetylated 1,5-lactone was produced by acetylation of ammonium 3-deoxy- d - manno -2-octulosonate or treatment of the pyridinium salt with dicyclohexylcarbodi-imide and acetylation. No lactone was produced when only HO-7 was unsubstituted. When treated with an excess of 2-methoxypropene, methyl (methyl 3-deoxy-α- d - manno -2-octulopyranosid)onate afforded the 4,5:7,8-di- O -isopropylidene derivative, from which the 7,8-acetal group could be removed selectively.

The reaction of malonaldehyde with periodate, and its application to the determination of vicinal diols in deoxy sugar derivatives

Abstract In dilute solution and at pH 3 to 5, triose reductone reduces three molar equivalents of periodate to iodate, and forms two molar equivalents of formic acid and one molar equivalent of carbon dioxide; iodine is not liberated in the process. Other ene-diols react similarly. At higher concentrations or lower pH values, iodine is liberated in all cases. Conditions in which malonaldehyde would react with stoichiometric amounts of periodate could not be found in the pH range of 1 to 8. It is shown that enolisation of malonaldehyde is faster than its reaction with periodate, and it was observed that malonaldehyde undergoes an unidentified chemical reaction at those pH values (3 to 5) where most periodate oxidations are carried out. At 4° in 0.1N sulphuric acid, malonaldehyde does not react with periodate over long periods of time, whereas glycol cleavage proceeds normally; therefore vicinal diol groups of deoxy sugars, deoxy sugar alcohols, and similar compounds can be titrated quantitatively in these conditions. The malonaldehyde formed can be estimated simultaneously by a calorimetric method, no standard being required. Syntheses of 3-deoxy- d - xylo -hexitol and of its pentabenzoate are described.

Synthesis of allyl 6-O-(3-deoxy-α- and -β-d-manno-oct-2-ulopyranosylonic acid)-(1 → 6)-2-deoxy-2-[(3R)-3-hydroxytetradecanamido]-β-d-glucopyranoside 4-phosphate and of the copolymer of the α anomer with acrylamide

Abstract The title disaccharides were synthesized by mercuric cyanide-catalyzed condensation of methyl (4,5,7,8-tetra- O -acetyl-3-deoxy-α- d - manno -oct-2-ulopyranosyl bromide)onate and allyl 2-[(3 R )-3-acetoxy-tetradecanamido]-3- O -benzyl-2-deoxy-β- d -glucopyranoside, followed by phosphorylation of the alcoholic function of the amino sugar. The phosphorylated anomers were separated by chromatography and deprotected by conventional methods. Polymeric material was obtained by copolymerisation, catalyzed by peroxosulphate and N,N,N′,N′ -tetramethylethylenediamine, of the α anomer with acrylamide; it contained ca . one disaccharide unit for 18 acrylamide residues.