The structure of the type-specific polysaccharide of Pneumococcus type XIX

The structure of the capsular polysaccharide of Type XIX Streptococcus pneumoniae (S-XIX) has been elucidated by ¹H- and ¹³C-n.m.r. spectroscopy. Mild hydrolysis of S-XIX with acid yielded a major oligosaccharide, the repeating unit of S-XIX, which was shown to be O-2-acetamido-2-deoxy-β-d-mannopyranosyl-(1→4)-O-α-d-glucopyranosyl-(1→2)-l-rhamnose 4′′-phosphate. Phosphoric acid forms a diester linkage in the S-XIX molecule, which explains the instability of S-XIX towards acid or alkali. The phosphodiester linkages in S-XIX join HO-1 of α-l-rhamnose and HO-4 of the 2-acetamido-2-deoxy-d-mannopyranosyl residue in the next repeating-unit. Treatment of S-XIX with alkali or alkaline-NaBH₄ produced the repeating units in a lower yield. The proposed structure of S-XIX is

     

The linkage of 4-O-methyl-L-galactose in the sulphated polysaccharide of Aeodes ulvoidea

Methyl 2-acetamido-5,6-di-O-benzyl-2-deoxy-β-d-glucofuranoside (11) was obtained in six steps from the known methyl 3-O-allyl-2-benzamido-2-deoxy-5,6-O-isopropylidene-β-d-glucofuranoside. Mild acid hydrolysis, followed by benzylation gave the 5,6-dibenzyl ether. The benzamido group was exchanged for an acetamido group by strong alkaline hydrolysis, followed by N-acetylation, and the allyl group was isomerized into a 1-propenyl group that was hydrolyzed with mercuric chloride. Treatment of 11 with l-α-chloropropionic acid and with diazomethabe gave methyl 2-acetamido-5,6-di-O-benzyl-2-deoxy-3-O-[d-1-(methoxycarbonyl)ethyl]-β-d-glucofuranoside which formed on mercaptolysis the internal ester 16, further converted into 2-acetamido-4-O-acetyl-5,6-di-O-benzyl-2-deoxy-3-O-[d-1-(methoxycarbonyl)ethyl]-d-glucose diethyl dithioacetal (18) by alkaline treatment followed by esterification with diazomethane and acetylation. Attempts to remove the O-acetyl group of the corresponding dimethyl acetal 20 with sodium methoxide in mild conditions were not successful.     

Synthèse du méthyl-2-acétamido-2-désoxy-β-D-glucofuranoside et de dérivés

Methyl 2-acetamido-2-deoxy-5,6-O-isopropylidene-β-D-glucofuranoside was prepared in excellent yield from methyl 2-benzamido-2-deoxy-5,6-O-isopropylidene-β-D-glucofuranoside by alkaline hydrolysis, followed by selective N-acetylation. Treatment with 60% acetic acid at room temperature gave syrupy methyl 2-acetamido-2-deoxy-β-D-glucofuranoside, characterized by a crystalline tri-O-p-nitrobenzoyl derivative. The same treatment, at 100° gave methyl 2-acetamido-2-deoxy-β-D-glucopyranoside. In an alternative procedure, the selective N-acetylation was performed after acetic acid hydrolysis of methyl 2-amino-2-deoxy-5,6-O-isopropylidene-β-D-glucofuranoside. Several derivatives of methyl 2-acetamido-2-deoxy-β-D-glucofuranoside were prepared and compared with the corresponding pyranosides. The furanoside structure was clearly demonstrated by mass spectrometry and periodate oxidation.     

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

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.     

2′-Azido-2′-deoxy- and 2′-amino-2′-deoxy-β-d-arabino-furanosyl purine nucleosides

A general method for the preparation of 2′-azido-2′-deoxy- and 2′-amino-2′-deoxyarabinofuranosyl-adenine and -guanine nucleosides is described. Selective benzoylation of 3-azido-3-deoxy-1,2-O-isopropylidene-α-d-glucofuranose afforded 3-azido-6-O-benzoyl-3-deoxy-1,2-O-isopropylidene-α-d-glucofuranose (1). Acid hydrolysis of 1, followed by oxidation with sodium metaperiodate and hydrolysis by sodium hydrogencarbonate gave 2-azido-2-deoxy-5-O-benzoyl-d-arabinofuranose (3), which was acetylated to give 1,3-di-O-acetyl-2-azido-5-O-benzoyl-2-deoxy-d-arabinofuranose (4). Compound 4 was converted into the 1-chlorides 5 and 6, which were condensed with silylated derivatives of 6-chloropurine and 2-acetamido-hypoxanthine. The condensation reaction gave α and β anomers of both 7- and 9-substituted purine nucleosides. The structures of the nucleosides were determined by n.m.r. and u.v. spectroscopy, and by correlation of the c.d. spectra of the newly prepared nucleosides with those published for known purine nucleosides.     

A substrate for the fluorogenic assay of exo-beta-N-acetylmuramidase: synthesis and purification of 4-methylumbelliferyl N-acetylmuramide.

A fluorogenic substrate for exo-β-N-acetylmuramidase from Bacillus subtilis B was synthesized. 4-Methyl-2-oxo-1,2-benzopyran-7-yl 2-acetamido-4,6-O-benzylidene-2-deoxy-β-d-glucopyranoside was prepared from 4-methyl-2-oxo-1,2-benzopyran-7-yl 2-acetamido-2-deoxy-β-d-glucopyranoside, condensed with dl-2-chloropropionic acid, the benzylidene residue removed by acetolysis and the 4-methyl-2-oxo-1,2-benzopyran-7-yl 2-amino-3-O-(d-1-carboxyethyl)-2-deoxy-β-d-glucopyranoside purified by chromatography on silica gel and Sephadex G-10 and by high-voltage paper electrophoresis. The identity of the product was confirmed by pmr studies, acid hydrolysis followed by chromatography of the products, and enzymic digestion.     

Specific conversion of d-galactose into d-galacturonic acid residues in glycoproteins: a facile method for carbohydrate linkage-analysis

The terminal d-galactopyranosyl residues of asialoglycopeptides isolated from human α₁-acid glycoprotein were oxidized in nearly quantitative yield to the corresponding uronic acid residues by a two-step sequence employing d-galactose oxidase followed by treatment with Tollens reagent, Ag(NH₃)₂⁺. Mild acid hydrolysis of the oxidized glycopeptides led to the isolation of the corresponding aldobiuronic acid(s). Structural and colorimetric analysis revealed that only one aldobiuronic acid, 2-amino-2-deoxy-4-O-(β-d-galactopyranosyluronic acid)-d-glucose, was isolated from the oxidized glycopeptides of α₁-acid glycoprotein. This method can readily distinguish between the (1→3), (1→4), and (1→6) isomers of the corresponding aldobiuronic acids.     

Oligonucleotide analogues containing internucleotide C3′-CH<Subscript>2</Subscript>-C(O)-NH-C5′ bonds

A dinucleoside bearing an amide internucleotide C3′-CH₂-C(O)-NH-C5′ bond was synthesized by the interaction of 3′-deoxy-3′-carboxylmethylribothymidine-2′,3′-lactone obtained by hydrolysis of 2′-O-acetyl-5′-O-benzoyl-3′-deoxy-3′-ethoxycarboxylmethylribothymidine with 5′-deoxy-5′-amino-3′-O-(tert-butyldimethylsilyl)thymidine. After standard manipulations with protective groups, the dinucleoside was converted into 3′-O-(2-cyanoethyl-N,N′-diisopropylphosphoroamidite), which was used for the synthesis of modified oligonucleotides on an automatic synthesizer. Duplex melting curves formed by modified and complementary natural oligonucleotides were measured and the melting temperatures and thermodynamic parameters of duplex formation were calculated. The introduction of one modified bond into oligonucleotides caused only an insignificant decrease in the duplex melting temperatures compared with the nonmodified ones.     

Pyruvic acid-containing mono- and oligo-saccharides from rhizobium trifolii bart A

After partial, acid hydrolysis of the extracellular, acid polysaccharide from Rh. trifolii Bart A, the following products were isolated and characterized: 3,4-O-(1-carboxyethylidene)-d-galactose, 4,6-O-(1-carboxyethylidene)-d-galactose, 3-O-[3,4-O-(1-carboxyethylidene)-β-d)-galactopyranosyl]-d-glucose, 3-O-[4,6-O-(1-carboxyethylidene)-β-d-galactopyranosyl]-d-glucose, O-[3,4-O-(1-carboxyethylidene)-β-d-galactopyranosyl ]-(1→3)-O-d-glucopyranosyl-(1→4)-d-glucose, and O-[4,6-O-(1- carboxyethylidene)-β-d-galactopyranosyl]-(1→3)-O-β-d-glucopyranosyl-(1→4)-d-glucose. The presence of pyruvic acid linked either to O-3 and O-4 or to O-4 and O-6 of the d-galactopyranosyl group of these saccharides indicates that both structures may be present in the original polysaccharide.     

Covalent structure of the extracellular polysaccharide from Xanthomonas campestris: evidence from partial hydrolysis studies.

Partial, acid hydrolysis of the extracellular polysaccharide from Xanthomonas campestris gave products that were identified as cellobiose, 2-O-(β-d-glucopyranosyluronic acid)-d-mannose, O(β-d-glucopyranosyluronic acid)-(1→2)-O-α-d-mannopyranosyl-(1→3)-d-glucose, O-(β-d-glucopyranosyluronic acid)-(1→2)-O-α-d-mannopyranosyl-(1→3)-[O-β-d-glucopyranosyl-(1→4)]-d-glucose, and O-(β-d-glucopyranosyluronic acid)-(1→2)-O-α-d-mannopyranosyl-(1→3)-[O-β-d-glucopyranosyl-(1→4)-O-β-d-glucopyranosyl-(1→4)-d-glucose. This and other evidence supports the following polysaccharide structure (1) which has been proposed independently by Jansson, Kenne, and Lindberg:

     

The action of Bacillus subtilis liquefying amylase on 6-deoxy-6-iodoamylose

Benzyl 2-acetamido-2-deoxy-3-O-β-D-galactopyranosyl-α-D-glucopyranoside (1) was chosen as a model bioside to develop a standard procedure for the selective cleavage of glycosidic linkages in polysaccharides containing 2-amino-2-deoxyhexose residues. Treatment of 1 with hydrazine in the presence of hydrazine sulphate resulted in quantitative N-deacetylation with the formation of benzyl 2-amino-2-deoxy-3-O-β-D-galactopyranosyl-α-D-glucopyranoside (2). The galactosyl glycosidic linkage in 2 could be selectively cleaved by acid hydrolysis. Oxidation of 2 with periodate destroyed the galactose residue. Treatment of 2 with nitrous acid cleaved the 2-amino-2-deoxy-D-glucosyl linkage to give 2,5-anhydro-3-O-β-D-galactopyranosyl-D-mannose (3) and benzyl alcohol.     

The synthesis of chlorodeoxyhexofuranoid derivatives

The reaction of 1,2-O-isopropylidene-α- d-glucofuranose with sulfuryl chloride at 0° and at 50° afforded 6-chloro-6-deoxy-1,2-O-isopropylidene-α- d-glucofuranose 3,5-bis(chlorosulfate) ( 3) and 5,6-dichloro-5,6-dideoxy-1,2-O-isopropylidene-β- l-idofuranose 3-chlorosulfate ( 7, not characterised), respectively. Dechlorosulfation of 3 afforded the hydroxy derivative, whereas treatment of 3 with pyridine gave the 3,5-(cyclic sulfate). Dechlorosulfation of 7 afforded 5,6-dichloro-5,6-dideoxy-1,2-O-isopropylidene-β- l-idofuranose which, on acid hydrolysis, was converted into 3,6-anhydro-5-chloro-5-deoxy- l-idofuranose. 5-Chloro-5-deoxy-α- l-idofuranosidurono-6,3-lactone and 5-chloro-5-deoxy-β- l-idofuranurono-6,3-lactone derivatives were also prepared.     

Riboside and Ribotide of 5(or 3)-Aminopyrazole-4-carboxamide

During the investigation for dephosphorylation of 4-hydroxy-1-β-D-ribofuranosylpyrazolo-[3,4-d] pyrimidine 5′-phosphate, it was found that the compound was converted to an unknown substance by alkaline hydrolysis for 3 hr at 140°C. The structure of the substance was assigned to be 5-amino-1-β-D-ribofuranosylpyrazole-4-carboxamide 5′-phosphate. 5(or3)-Amino- pyrazole-4-carboxamide and its riboside were also obtained from 4-hydroxypyrazolo [3,4-d] pyrimidine and its riboside, respectively, under the similar conditions.

5-Amino-1-β-D-ribofuranosyipyrazole-4-carboxamide and 5-amino-1-β-D-ribofuranosyl- pyrazole-4-carboxamide 5′-phosphate are new compounds.     

One-flask synthesis of triacetalated aldohexoses with 2,2-dialkoxypropane and p-toluenesulfonic acid

2-Deoxy-d-arabino-hexose and some N-protected 2-amino-2-deoxy-d-glucose derivatives were each treated with 2,2-dimethoxy- or 2,2-dibenzyloxy-propane in 1,4-dioxane in the presence of p-toluenesulfonic acid at 60–70°. The major products were acyclic, dimethyl and dibenzyl acetals of 2-deoxy-3,4:5,6-di-O-isopropylidene-aldehydo-d-arabino-hexose or of N-protected 2-amino-2-deoxy-3,4:5,6-di-O-isopropylidene-aldehydo-d-glucose. Some of the dibenzyl acetals were converted into the corresponding 3,4:5,6-di-O-isopropylidene-aldehydo-d-hexoses in good yield.     

Synthesis of 2-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-D-mannose,and its interaction with D-mannose-specific lectins

Condensation of 3,4:5,6-di-O-isopropylidene-D-mannose dimethyl acetal with 2-methyl-(3,4,6-tri-O-acetyl- 1,2-dideoxy-α-D-glucopyrano)-[2′, 1′:4,5]-2-oxazoline in the presence of a catalytic amount of p-toluenesulfonic acid afforded crystalline 2-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-D-glucopyranosyl)-3,4:5,6-di-O-isopropylidene-D-mannose dimethyl acetal (3) in 25% yield. Catalytic deacetylation of 3 with sodium methoxide, followed by hydrolysis with dilute sulfuric acid, gave 2-O-(2-acetamido-2-deoxy-α-D-glucopyranosyl)-D-mannose (4). Treatment of 3 with boiling 0.5% methanolic hydrogen chloride under reflux gave methyl 2-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-α-D-mannopyranoside (5) and methyl 2-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-α-D-mannofuranoside (6). The inhibitory activities of 4, 5, and 6 against the hemagglutinating and mitogenic activities of Lens culinaris and Pisum sativum lectins and concanavalin A were assayed. From the results of these hapten inhibition studies, subtle differences of specificity between these D-mannose-specific lectins were confirmed.     

Epoxyalkyl oligo-(1 leads to 4)- -D-glucosides as active-site-directed inhibitors of cellulases

N-Deacetylation of benzyl 2-acetamido-2-deoxy-6-O-α-D-mannopyranosyl-α-D-glucopyranoside (3) by alkaline hydrolysis, or hydrazinolysis in the presence of hydrazine sulphate, proceeds quantitatively to yield the amine 4. The mannosyl glycosidic linkage in 4 can be selectively hydrolysed by acid, whereas the 2-amino-2-deoxyhexosyl glycosidic linkage is selectively cleaved upon treatment with sodium nitrite in dilute acetic acid. Aspects of the selective cleavage of hexosaminoglycans are discussed.     

Buffer induced modification of 6-sulfated disaccharide in chondroitin lyase digestions

High-performance liquid chromatographic analyses of chondroitin lyase AC or ABC hydrolysates revealed unexpected high content of material coeluting with the nonsulfated disaccharide 2-acetamido-2-deoxy-3-O-(β-d-gluco-4-enepyranosyl uronic acid)-d-galactose. Incubation of a commercial preparation of the 6-sulfated disaccharide, 2-acetamido-2-deoxy-3-O-(β-d-gluco-4-enepyranosyl uronic acid)-6-O-sulfo-d-galactose with “enriched Tris buffer” generated material coeluting with nonsulfated disaccharide. The amount of material exhibiting this anomalous chromatographic behavior was proportional to the amount of 6-sulfated disaccharide added to the incubation mixture. This suggested a precursor/product relationship between the 6-sulfated disaccharide and the anomalous peak. The result was specific for the 6-sulfated disaccharide: incubation of the 4-sulfated disaccharide, 2-acetamido-2-deoxy-3-O-(β-d-gluco-4-enepyranosyl uronic acid)-4-O-sulfo-d-galactose, with enriched Tris buffer did not generate material with anomalous chromatographic properties. When [³⁵S]sulfate labeled cartilage glycosaminoglycans were hydrolyzed with chondroitin lyases, some of the radioactivity coeluted with the nonsulfated disaccharide. Thus, buffer-induced modification of 6-sulfated disaccharide was not caused by hydrolysis of ester sulfate. Although the proportion of the 6-sulfated disaccharide which was recovered in the anomalous peak was constant for incubations done simultaneously, incubations done at different times gave variable results. Thus, control incubations of 6-sulfated disaccharide with chondroitinase buffer must be included with each reaction series to allow correction for the proportion of the material eluting with nonsulfated disaccharide which is actually 6-sulfated.     

The synthesis of P1-2-acetamido-4-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-2-deoxy-α-d-glucopyranosyl P2-dolichyl pyrophosphate, (P1-di-N-acetyl-α-chitobiosyl P2-dolichyl pyrophosphate)

2-Acetamido-4-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-2-deoxy-α-d-glucopyranosyl phosphate, pure according to thin-layer and gas—liquid chromatography, optical rotation, and treatment with alkaline phosphatase and 2-acetamido-2-deoxy-β-d-glucosidase, was prepared by treatment of 2-methyl-[4-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-d-glucopyranosyl)-3,6-di-O-acetyl-1,2-dideoxy-α-d-glucopyrano]-[2,1-d]-2-oxazoline with dibenzyl phosphate, followed by the removal of the benzyl groups by catalytic hydrogenolysis, and O-deacetylation. In contrast, a sample prepared by the phosphoric acid procedure was shown to consist mainly of the β anomer. 2-Acetamido-4-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-d-glucopyranosyl)-3,6-di-O-acetyl-2-deoxy-α-d-glucopyranosyl phosphate was treated wit P¹-diphenyl P²-dolichyl pyrophosphate to give a fully acetylated pyrophosphoric diester, which was O-deacetylated to give P¹-2-acetamido-4-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-2-deoxy-α-d-glucopyranosyl P²-dolichyl pyrophosphate. This compound could be separated from the β anomer by t.l.c., and its behavior under dilute acid and alkaline conditions was investigated.     

Depolymerization of heparin with diazomethane. Structure of N,O-methylated,even-numbered oligosaccharides produced by β-eliminative cleavage of the 2-amino-2-deoxyglycosylic linkage

The long-period reaction of heparin with excess diazomethane at 20° resulted in cleavage at the β-position of the uronic acid carboxyl group to give a mixture of methyl α- and β-glycosides of N,O-methylated di-, tetra-, and hexa-saccharides having a 4,5-unsaturated uronic acid, nonreducing end-group. The major disaccharides obtained were methyl O-(4-deoxy-3-O-methyl-α-l-threo-hex-4-enopyranosyluronic acid 2-sulfate)-(1→4)-2-deoxy-3-O-methyl-2-(N-methylsulfoamino)-α- and -β-d-glucopyranoside. The reaction of heparin at 4° yielded a mixture of methylated, higher-molecular-weight oligosaccharides, which retained some affinity for antithrombin III-Sepharose.