Studies of the binding activity of phage G13 to synthetic trisaccharides analogous to binding structures in Salmonella typhimurium and Escherichia coli C core saccharide. Correlation between conformation and binding activity

Phage G13 binds to the carbohydrate part of lipopolysaccharides from rough mutants of Salmonella and Escherichia coli as the first event of infection. Equilibrium dialysis inhibition studies with native and synthetic trisaccharides as inhibitors suggested that phage G13 recognizes branched oligosaccharides having 6-O-alpha- or 7-O-alpha-glycosyl groups with alpha-Man(1----3) [alpha-Man(1----6)]Man (Man[Man]Man) and alpha-Glc(1----3)-[alpha-Hep(1----7)] alpha-Hep(1----3) alpha-Hep(1----5)Kdo as the smallest saccharides with inhibitory activity (Wollin et al., 1989). Of four synthetic analogues to Man[Man]Man only Man(1----3)[alpha-Gal(1----6)]alpha-Man-OMe (Man[Gal]-Man) and alpha-Glc(1----3)[alpha-Hep(1----7)]alpha-Hep-OMe (Glc[Hep]Hep) inhibited the binding of labelled E. coli C core nonasaccharide ligand to G13 with activities which were 10- and 15-fold lower than Man[Man]Man. The trisaccharides alpha-Man(1----3)[alpha-Glc(1----6)[alpha-Man-OMe (Man[Glc]Mann) and alpha-Man(1---3)[alpha-Tal(1----6)]alpha-Man-OMe (Man[Tal]Man) showed no inhibition at concentrations 75-fold higher than Man[Man]Man. Minimum energy conformation calculations of the saccharides using the GESA method showed that the 6-O-alpha-Man group in Man[Man]Man and the 7-O-alpha-Hep group SL805 pentasaccharide expose their OH-2 and OH-3 groups in a similar way and these are postulated to be key structural features for binding activity. The importance of hydroxy groups at certain positions is implied from the fact that both manno- and galacto-isomers are active. We also conclude that the O6-C6-C5-O5-C1 region of the 3-O-alpha-glycosyl group in the Man[Man]Man trisaccharide, or part of it, is important for the G13 binding activity.

Isolation and characterization of new allosamidins

Three of new allosamidins, termed glucoallosamidins A (5), B (6) and methyl-N-demethyl-allosamidin (4), were isolated as yeast chitinase inhibitors from the mycelium of Streptomyces sp. SA-684.

Interactions of five D-mannose-specific lectins with a series of synthetic branched trisaccharides

The interaction of a series of synthetic, branched trisaccharides with five D-mannose-specific lectins was studied by precipitation-inhibition assay. The branched methyl alpha-D-mannotrioside, alpha-D-Manp-(1----3)-[alpha-D-Manp-(1----6)]-alpha-D-Man pOMe, the best inhibitor of the Con A-Dextran interaction, was 42 times more potent than alpha-D-ManpOMe, and 3-6 times more potent than the two trisaccharides substituted with D-glucosyl groups, and 8-15 times those with D-galactosyl groups. Surprisingly, methyl O-alpha-D-mannopyranosyl-(1----3)-alpha-D-mannopyranoside was bound to Con A 8-fold more avidly than methyl alpha-D-mannopyranoside. However, the related pea lectin (PSA) was singularly different from Con A in its carbohydrate-binding activity, showing no significantly enhanced binding to any of the sugars examined. The trisacchrides containing terminal, nonreducing, (1----3)-linked alpha-D-mannopyranosyl groups, i.e., alpha-D-Manp-(1----3)-[alpha-D-Glep-(1----6)]alpha-D-Manp OMe, alpha-D-Manp-(1----3)]-alpha-D-Galp-(1----6)]-alpha-D-ManpOMe++ +, and alpha-D-Manp-(1----3)-[alpha-D-Manp-(1----6)]-alpha-D-Man pOMe, were the best inhibitors of the snowdrop lectin (GNA)-D-mannan precipitation system. On the other hand, all branched trisaccharides exhibited very similar inhibitory potencies toward the daffodil lectin (NPA)-D-mannan interaction, whereas alpha-D-Manp-(1----3)-[alpha-D-Galp-(1----6)]-alpha-D-ManpOMe++ + and alpha-D-Manp-(1----3)-[alpha-D-Manp-(1----6)]-alpha-D-Man pOMe were somewhat better inhibitors than the other branched trisaccharides of the amaryllis lectin (HHA)-D-mannan precipitation reaction. (ABSTRACT TRUNCATED AT 250 WORDS)

Structure and solution conformations of a cyclic trisaccharide from high-resolution n.m.r. spectroscopy and molecular modelling

The conformational properties of a cyclic trisaccharide: [O-beta-D-glucopyranosyl-(1----6)]3 1,6"-anhydride nonacetate (C36H48O24, 1) have been established by high-resolution 1H- and 13C-n.m.r. spectroscopy in conjunction with potential-energy and molecular-mechanics calculations. The n.m.r. parameters used were nuclear Overhauser enhancements (n.O.e.) and coupling constants. From theoretical models of the trisaccharide, a statistical-mechanics approach was used to compute an ensemble average-relaxation matrix from which the n.O.e. were calculated. The observed nuclear Overhauser enhancements as measured by n.m.r. spectroscopy may be satisfactorily modelled if averaging over two conformational states is considered. In solution, both conformations of the molecule exhibit three-fold symmetry; the beta-linked glucopyranose rings have the 4C1 conformation. In one conformer, the orientation about the (1----6) linkage is characterized by torsion angles phi = 79.5 degrees, psi = 143.5, and omega = -64.3. For the other conformer, these values are phi = -137.7, psi = 68.2, and omega = 45.6. The existence of such a conformer shows that solution behaviour is not dominated by the stabilizing influence of the exoanomeric effect.

Reaction mechanism and fragment ion structure determination of deprotonated small oligosaccharides, studied by negative ion fast atom bombardment (tandem) mass spectrometry

The negative ion mass spectrometric characteristics of a series of di- and trisaccharides and the tetrasaccharide stachyose have been studied using fast atom bombardment mass spectrometry. The molecular weight of the compounds can easily be derived from their mass spectra, which all show an abundant [M - H]- ion peak. The application of metastable ion and collisional activation techniques to selected pseudomolecular and fragment ions appears to be appropriate for the determination of the position and anomeric type of linkage in the molecules, and provides information concerning the monosaccharide units involved. Important fragmentation reactions have been traced and reaction mechanisms, supported by deuterium labelling experiments, are proposed. An experiment describing the application of the findings of this study to a glycosphingolipid molecule demonstrates its potential value for biological systems.

Vibrational Raman optical activity of carbohydrates

Vibrational Raman optical activity (R.o.a.) spectra of a range of carbohydrates in aqueous solution, measured in back-scattering between 700 and 1500 cm-1, are presented. Features were revealed that appear to be characteristic of details of the stereochemistry. Effects associated with the glycosidic linkage in di- and oligo-saccharides are prominent.

Positive ion fast atom bombardment mass spectrometry of some small oligosaccharides

Positive ion fast atom bombardment mass spectrometry appears to be a very useful method for the determination of molecular weight and composition of underivatized di- and trisaccharides. Information on the identity of the monosaccharide units can be obtained from the metastable ion and collisional activation spectra of selected ions. The type of linkage between the monosaccharides is reflected in some spectral characteristics, but the differences are relatively small and do not always allow an unambiguous identification. The position of a fructose unit in a trisaccharide molecule is shown by the collisional activation spectra of the [M + H]+ ion, as an anhydrofructose molecule is easily eliminated from the ions in which fructose is in a terminal position.

Synthesis of the oligosaccharides alpha-D-Glcp-(1----4)-D-Xylp, alpha-D-Xylp-(1----4)-D-Glcp, alpha-D-Glcp-(1----4)-alpha-D- Glcp-(1----4)-D-Xylp, alpha-D-Glcp-(1----4)-alpha-D-Xylp-(1----4)- D-Glcp, and alpha-D-Xylp-(1----4)-alpha-D-Glcp-(1----4)-D-Glcp

Syntheses are described of the disaccharides, alpha-D-Glcp-(1----4)-D-Xylp, alpha-D-Xylp-(1----4)-D-Glcp, and alpha-D-Xylp-(1----4)-D-Xylp, and the trisaccharides, alpha-D-Glcp-(1----4)-alpha-D-Glcp-(1----4)-D-Xylp, alpha-D-Glcp-(1----4)-alpha-D-Xylp-(1----4)-D-Glcp, and alpha-D-Xylp-(1----4)-alpha-D-Glcp-(1----4)-D-Glcp as analogues of glucoamylase and soybean beta-amylase substrates.

Isolation and characterization of a lectin from the cephalochordate Branchiostoma lanceolatum (Pallas)

1. A lectin was isolated from an extract of Branchiostoma lanceolatum by affinity chromatography using an asialo-A-peptone-cellulose column. 2 The lectin is a glycoprotein with a carbohydrate content of 2.7%. The mol. wt is 392,000 +/- 28,000. Two subunits of identical size (183,000 +/- 3000) are linked by non-covalent bonds. 3. The lectin agglutinates a variety of erythrocytes including human A, B, O red blood cells as well as human lymphocytes. 4. Hemagglutination activity is inhibited best by N,N',N"-triacetylchitotriose, followed by N,N'-diacetylchitobiose, which is half as inhibitory. 5. Lectin activity is constant between pH 5 and 10. Divalent cations are not required for binding reactions. Activity is totally destroyed by heating to 60 degrees C for 30 min. 6. The lectin is precipitated from the extract by 30-40% ammonium sulfate saturation.

Thomsen-Friedenreich (T)-active glycoproteins, blood group N antigen precursor glycoproteins and N antigen precursor glycoproteins with T activity from ascitic fluids of liver cancer patients

1. Five perchloric acid-soluble fractions (PASFs) obtained from ascitic fluids of three patients with primary hepatocellular carcinoma (HCC), a patient with liver metastatic carcinoma (LUC) from ureteral carcinoma and human normal serum (NS) were subjected to DEAE-cellulose column chromatography to separate seven glycoprotein fractions, respectively. 2. In this chromatography, two HCC-PASFs gave a Thomsen-Friedenreich (T)-active glycoprotein, respectively. 3. Other HCC-PASF gave a T-active glycoprotein, two blood group N antigen precursor glycoproteins and an N antigen precursor glycoprotein with T activity. 4. LUC-PASF gave two T-active glycoproteins and an N antigen precursor glycoprotein with T activity. 5. NS-PASF did not give these serologically active glycoproteins.

Interconversion of radical and nitrone forms of lysodektose--a new trisaccharide from Micrococcus lysodeikticus

Isolated from Micrococcus lysodeikticus, 6-O-(2-deoxy-2-(N-methyl)hydroxilamino-beta-D-glucopyranosyl)-alph a-alpha- trehalose (lysodektose) is oxidized by K3Fe(CN)6 in a stepwise manner to become a nitroxyl radical and a nitrone with a double bond in the fragment O-N = CH2 which could be reduced to the original hydroxylamine form with sodium borohydride. Thus derivatives of lysodektose specifically labelled with 2H and (or) 3H in the methyl group are easily obtained. When oxidized in cells poisoned with vitamin K analogues, lysodektose is transformed into nitrone concomitant with modification of its methyl group. Participation in the antioxidant defence of the bacteria is suggested for this new trisaccharide.

Lysodektose--a new trisaccharide from Micrococcus lysodeikticus which is transformed into an aminoxyl free radical with the loss of an electron

A new trisaccharide 6-0-(2-deoxy-2-(N-methyl)-hydroxylamino-beta-D- glucopyranosyl)-alpha,alpha-trehalose named lysodektose has been isolated from Micrococcus lysodeikticus. In oxygenated solutions or in the presence of K3 Fe (CN)6 lysodektose is transformed into a long lived free radical. Spin trapping data are presented and functions are suggested for the substance.

Acetylation at O-2 of arabinofuranose residues in feruloylated arabinoxylan from bamboo shoot cell-walls

Hydrolysis of bamboo shoot cell-walls with Driselase (a fungal enzyme preparation) gave an arabinoxylan trisaccharide with ferulic and acetic acids as ester groups. The structure of this oligosaccharide was determined to be O-[2-O-acetyl-5-O-[E)-feruloyl)-alpha-L-arabinofuranosyl]-(1----3) -O-beta- D-xylopyranosyl-(1----4)-D-xylopyranose, on the basis of spectroscopy and methylation analysis.

Sialyl-alpha 2-6-mannosyl-beta 1-4-N-acetylglucosamine, a novel compound occurring in urine of patients with beta-mannosidosis

Human beta-mannosidosis urine was fractionated by gel permeation chromatography on Bio-Gel P-2 and by high performance liquid chromatography on Partisil 10 SAX. Besides the disaccharide Man beta 1-4GlcNAc as the major component, a sialic acid-containing compound was detected in an amount of 10% compared to that of Man beta 1-4GlcNAc. Structural characterization of the oligosaccharide and of its reduced analogue by sugar composition analysis, methylation analysis, gas-liquid chromatography-mass spectrometry, and 500-MHz 1H NMR spectroscopy gave conclusive evidence for a novel urinary constituent: NeuAc alpha 2-6Man beta 1-4GlcNAc. This linear trisaccharide can be considered as the result of an alpha 2-6-sialylation of the major accumulating compound, Man beta 1-4GlcNAc. The hitherto unknown linkage between sialic acid and mannose was shown to be susceptible to sialidase digestion.

Synthesis of a peripheral trisaccharide sequence of lutropin, a pituitary glycoprotein hormone; use of chitobiose as a key starting material

A chitobiose derivative, methyl O-(3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl)-(1--- -4)-3,6 - di-O-acetyl-2-deoxy-2-phthalimido-beta-D-glucopyranoside, was derived from the corresponding N-acetyl derivative and this was converted into the glycosyl bromide (5). Glycosidation reaction between 5 and methyl 3,4,6-tri-O-benzyl-alpha-D-mannopyranoside in the presence of silver trifluoromethanesulfonate gave a beta-D-linked trisaccharide derivative. Replacement of the N,N-phthaloyl group by acetyl groups resulted in a product that was converted into methyl O-(2-acetamido-3,6-di-O-benzyl-2-deoxy-beta-D-glucopyranosyl)-(1----4)-O -(2- acetamido-3,6-di-O-benzyl-2-deoxy-beta-D-glucopyranosyl)-(1----2)-3,4,6- tri-O- benzyl-alpha-D-mannopyranoside (11) by use of a few reaction steps. The 4(3)-hydroxyl group of 11 was methanesulfonylated, and the product subjected to SN2 replacement with acetate anion, to give the D-galactosamine-containing trisaccharide derivative (12). After basic hydrolysis of 12, the 4(3)-hydroxyl group was sulfated, and all benzyl groups were removed by hydrogenolysis, giving methyl O-(2-acetamido-2-deoxy-4-O-sulfo-beta-D-galactopyranosyl)-(1----4)-O-(2- acetamido-2-deoxy-beta-D-glucopyranosyl)-(1----2)-alpha-D-mannopyranosid e monosodium salt, the methyl alpha-glycoside derivative of the peripheral trisaccharide sequence of the pituitary glycoprotein hormone lutropin.

Hydrolysis of (1----3)- and (1----2)-beta-D-xylosidic linkages by an endo-(1----4)-beta-D-xylanase of Cryptococcus albidus

The substrate specificity of an endo-(1----4)-beta-D-xylanase of the yeast Cryptococcus albidus was investigated using a series of methyl beta-D-xylotriosides. In addition to (1----4) linkages, the enzyme could cleave (1----3) and (1----2) linkages adjacent to a (1----4) linkage and further from the non-reducing end of the substrate. The enzyme could hydrolyse a (1----3) linkage that attached a terminal xylopyranosyl group to a (1----4)-linked xylobiosyl moiety. The enzyme did not attack alpha-D-xylosidic linkages. The rate of cleavage of (1----4) linkages was much higher than those of other linkages at 0.5mM substrate, but the rates were comparable at 20mM substrate when transglycosylation reactions also occurred that facilitated degradation of the substrates.

Synthesis of methyl 3-O-(alpha-D-glucopyranosyl)-7-O-(L-glycero-alpha-D- manno-heptopyranosyl)-L-glycero-alpha-D-manno-heptopyranoside

The title trisaccharide glycoside, which is related to part of the core region of the lipopolysaccharide from Salmonella, and the disaccharide glycosides methyl 3-O-alpha-D-glucopyranosyl-L-glycero-alpha-D-manno-heptopyranoside and methyl 7-O-L-glycero-alpha-D-manno-heptopyranosyl-L-glycero-alpha-D-manno- heptopyranoside have been synthesised. Methyl 2,3,4-tri-O-benzyl-L-glycero-alpha-D-manno- heptopyranoside, obtained via a one-carbon elongation at C-6 of methyl 2,3,4-tri-O-benzyl-alpha-D-manno- hexodialdo-1,5-pyranoside, was used as precursor both for the heptosyl donor and acceptor.

Synthesis of a tri- and a tetra-saccharide fragment of the capsular polysaccharide of type III group B Streptococcus

Syntheses of the propyl glycosides (1-3) of beta-D-Galp-(1----4)-beta-D-GlcpNAc, beta-D-Glcp-(1----6)-[beta-D-Galp-(1----4)]-beta-D-GlcpNAc, and beta-D-Galp-(1----4)-beta-D-Glcp-(1----6)-[beta-D-Galp-(1----)]-beta-D- GlcpNAc, respectively, are reported. Reaction of allyl 2-acetamido-3-O-benzyl-2-deoxy-6-O-(4-methoxybenzyl)-beta-D-glucopyranos ide with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide under Hg(CN)2 catalysis, followed by oxidative removal of the 4-methoxybenzyl group, gave allyl 2-acetamido-3-O-benzyl-2-deoxy-4-O-(2,3,4,6-tetra-O-acetyl-beta-D- galactopyranosyl)-beta-D-glucopyranoside (10) O-deacetylation of which, followed by hydrogenolysis/hydrogenation, gave 1. Reaction of 10 with beta-D-glucopyranose penta-acetate and beta-lactose octa-acetate, under catalysis by trimethylsilyl trifluoromethanesulfonate, and treatment of the products as for 10 gave 2 and 3, respectively. Attempted glycosylation of 10 with 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl bromide under catalysis by Hg(CN)2 or silver trifluoromethanesulfonate gave an orthoester. Complete assignments of the 1H- and 13C-n.m.r. spectra of 1-3 are reported together with their carbon spin-lattice relaxation times which indicate that 3 assumes a compact instead of an extended shape.

Stereoselective total synthesis of dodecagalacturonic acid, a phytoalexin elicitor of soybean

O-(alpha-D-Galactopyranosyluronic acid)-[(1----4)-O-(alpha-D-galactopyranosyluronic acid)]10-D-galactopyranuronic acid (1), an endogenous elicitor of the phytoalexin of soybean, was synthesized by way of highly stereoselective glycosylations that involved glycosyl fluorides as the donors and oxidation of the twelve primary hydroxyl groups in the alpha-(1----4)-linked galactododecaoside derivative.

Structure determination of five sialylated trisaccharides with core types 1, 3 or 5 isolated from bovine submaxillary mucin

In this study we have investigated the structures of five sialylated trisaccharides released from bovine submaxillary mucin by alkaline borohydride treatment and isolated by high-performance liquid chromatography. Three of the trisaccharides contained NeuAc while two contained NeuGc. One oligosaccharide contained core-type 1, two contained core-type 3 and two contained core-type 5. The structures, determined by a combination of one- and two-dimensional 1H-NMR spectroscopy at 270 MHz and methylation analysis involving gas-liquid chromatography/mass spectrometry, were as follows: A4b, GalNAc alpha(1----3) [NeuAc alpha(2----6)]GalNAcol; A4c, GlcNAc beta(1----3)[NeuAc alpha(2----6)]GalNAcol; A4d, Gal beta(1----3)[NeuAc alpha(2----6)]GalNAcol; A4e, GalNAc alpha(1----3)-[NeuGc alpha(2----6)]GalNAcol; A4f, GlcNAc beta(1----3)[NeuGc alpha (2----6)]GalNAcol. The oligosaccharides occurred in the approximate molar ratios 1.0:12.0:0.3:0.2:2.0. This is the first report of oligosaccharides containing core-type 5 and of the occurrence of oligosaccharides A4b, A4e, and A4f in bovine submaxillary mucin. 1H-NMR data for structure A4e, which is a novel structure, are presented for the first time.

Synthesis and characterisation of methyl 2-O-(beta-D- glucopyranosyl)-6-O-(alpha-L-rhamnopyranosyl)-alpha-D-glucopyranoside

The branched trisaccharide, 2-O-(beta-D-glucopyranosyl)-6-O-(alpha-L-rhamnopyranosyl)-D-glucopyranos e (2), is regarded as the sugar moiety of an anthocyanin pigment isolated from the fruits and flowers of certain Begonia, Clivia, Rubus, Prunus, and Ribis species. The cyanidin-3-glycoside of 1 has been identified as one of the major pigments of Montmorency cherries (Prunus cerasus). It has also been isolated as quercetin and kaempherol glycosides from the flowers of potato (Solanum tuberosum). Synthesis of the methyl glycoside of 1, methyl 2-O-(beta-D-glucopyranosyl)-6-O-(alpha-L-rhamnopyranosyl)-alpha-D-glucop yranoside (2) is reported.

G.l.c.-m.s. of partially methylated and acetylated derivatives of L-glycero-D-manno- and D-glycero-D-manno-heptopyranoses and -heptitols

Methylated or acetylated heptopyranose derivatives were prepared variously from L-glycero-D-manno- and D-glycero-D-manno-heptopyranose, O-L- glycero-alpha-D-manno-heptopyranosyl-(1----3)-L-glycero-D-manno- heptopyranose, O-L-glycero-alpha-D-manno-heptopyranosyl-(1----7)-L-glycero- D-manno-heptopyranose, and O-L-glycero-alpha-D-manno- heptopyranosyl-(1----7)-O-L-glycero-alpha-D-manno- heptopyranosyl-(1----3)-L-glycero-D-manno- heptopyranose, which are structural elements of the heptose region of enterobacterial lipopolysaccharides. Each derivative was investigated by g.l.c. and g.l.c.-m.s., and the retention times and fragmentation patterns were used to identify partial structures of the heptose region of the core oligosaccharide of bacterial LPS.