M. Stacey

The oxidation of some carbohydrate derivatives, using acid anhydride-methyl sulphoxide mixtures and the pfitzner-moffatt reagent. Facile synthesis of 3-acetamido-3-deoxy-D-glucose and 3-amino-3-deoxy-D-xylose

Examples are provided which further demonstrate the value of the Pfitzner-Moffatt reagent and acid anhydride-methyl sulphoxide mixtures as oxidants in carbohydrate chemistry. Convenient and stereospecific syntheses of 3-acetamido-3-deoxy-D-glucose and 3-amino-3-deoxy-D-xylose have been developed from 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose.

β-d-glucosidase chemically bound to microcrystalline cellulose☆

Abstract Almond β- d -glucosidase reacts with cellulose carbonate to give an enzymically active, insoluble, enzyme derivative. The coupling reaction is pH-dependent, the optimum being at pH ∼7.8. The bound enzyme is more stable than the free form to incubation at 37°. The pH-activity profile for the bound is similar to that for the free enzyme.

The automated spectrofluorimetric determination of formaldehyde in the periodate oxidation of carbohydrates and amino acids

Abstract The automated spectrofluorimetric determination of formaldehyde, released by periodate oxidation, as 3,5-diacetyl-1,4-dihydro-2,6-dimethylpyridine is described. The application of the method, with modifications where necessary, to the monitoring of various procedures for fractionation of carbohydrates is outlined, and the sensitivity of the automated method is compared with the less-sensitive colorimetric method. The response of various amino acids in the assay system has been investigated and reveals the applicability of the method to serine in particular and the caution necessary in periodate oxidation of carbohydrates in the presence of free amino acids.

Some structural studies of brea gum (an exudate from Cercidium australe jonhst.)

Abstract The gum exudate (brea gum) from the leguminous tree Cercidium australe contains residues of l -arabinose, d -xylose, d -glucuronic acid, and 4- O -methyl- d -glucuronic acid, in the approximate molar ratios of 1,7:6,3:1,9:0,9. Autohydrolysis of the gum afforded (chromatographic identification) xylobiose (and homologues), 2- O - and 4- O -(α- d -glucopyranosyluronic acid)- d -xylose, and 2- O -(4- O -methyl-glucopyranosyluronic acid)- d -xylose. The principal, neutral components of the methylated gum were 3- O - and 2,3,4-tri- O -methyl- d -xylose; by chromatographic methods, 2,3-di- O -methyl- d -xylose and - l -arabinose, and a tri- O -methylarabinose were also detected. After reduction, the acidic products from the methylated gum gave, inter alia , 3,4-di- O -methyl- d -glucose and 2,3,4-tri- O -methyl- d -glucose (chromatographic identification). The major structural features of brea gum appear to be a β-(1 → 4)-linked d --xylan backbone [possibly containing some (1 → 2)-linkages] that is heavily 2-substituted by short branch-chains containing residues of d -xylose (and l -arabinose) and d -glucuronic acid, in which both types of residue may be terminal. Approximately one-third of the uronic acid is present as the 4-methyl ether, and, in the purified polysaccharide, a similar proportion of the acid residues is lactonised. Supporting evidence for these features was obtained by periodate-oxidation studies of the carboxyl-reduced polysaccharide.

Linkage analysis of carbohydrates by using saccharinic acid formation

Abstract Methods for assaying isosaccharinic, metasaccharinic, and saccharinic acids on a microgram scale are described; these may be used to monitor the production of such acids during the alkali-mediated, “peeling” reaction of oligosaccharides. These methods of assay, coupled with determination of the formaldehyde produced following periodate oxidation of the equilibrium degradation mixture, are proposed for use in linkage analysis of oligosaccharides containing hexoses or hexuloses.

Arrangement of the l-rhamnose units in Diplococcus pneumoniae Type II polysaccharide

Abstract Pneumococcus Type II polysaccharide, containing l -rhamnose (47.8%), d -glucose (34.7%), and sodium d -glucuronate (16.2%), induced sequentially in cultures of Klebsiella aerogenes an α- l -rhamnosidase, which liberated O -β- l -rhamnopyranosyl-(1→3)- O -β- l -rhamnopyranosyl-(1→3)- l -rhamnose, and then a β- l -rhamnosidase, which degraded this trisaccharide to l -rhamnose. The arrangement of such rhamnose units in the polysaccharide has been determined by using sequential application of degradation by periodate oxidation, sodium borohydride reduction, and mild acid hydrolysis, and repetitions of this sequence.

G.L.C. of the O-trimethylsilyl derivatives of hexuronic acids.

The free acids, sodium salts, and lactones of several hexuronic acids have been studied as their O-trimethylsilyl derivatives by gas-liquid chromatography using SE-30 and XE-60 liquid phases. Silylation was best performed in methyl sulphoxide. The equilibrium between the various forms of a hexuronic acid in methyl sulphoxide was also studied by g.l.c. following silylation. The hexamethyldisilazane used in the silylation disturbed the equilibrium attained in the solvent, but this was overcome by premixing the hexamethyldisilazane with chlorotrimethylsilane. Methyl sulphoxide and the silylating reagents gave a two-phase system in which the derivative was favourably partitioned into the upper layer. Partition coefficients and stabilities of the derivatives were measured, and a g.l.c. method for the analysis of the hexuronic acids was thereby developed. The oximes of the hexuronic acids were studied as alternative derivatives for g.l.c., and their equilibrium compositions and g.l.c. retention times are recorded.

Oxidative alkaline degradation of cellobiose

The nature and concentrations of products arising from the alkaline degradation of cellobiose were determined by varying the base, base concentration, sugar concentration, temperature, and atmosphere within the reaction vessel. In nitrogen, the oxidation reactions could effectively be eliminated. By introducing oxygen at various concentrations, oxidation reactions to aldonic acids predominated. The major acids found from the reducing end were 3,4-dihydroxybutyric acid and isosaccharinic acid, whilst d-arabinonic and glyceric acids were formed from the nonreducing end. In the stopping reaction, the major bound acids were 3-O-β-d-glycopyranosyl-d-arabinonic acid, 2-O-β-d-glucopyranosyl-d-erythronic acid, and 4-O-β-d-glucopyranosyl-d-mannonic acid. The yields of isosaccharinic and aldonic acids varied as the base and sugar concentrations were changed, and this clearly illustrated that the conditions of alkaline degradation determined the proportions of products obtained.

Sequence studies on diplococcus pneumoniae type II polysaccharide

Abstract Assay of formic acid released by periodate oxidation of Diplococcus pneumoniae Type II polysaccharide (SII), during liberation of an L -rhamnose-containing trisaccharide from SII by α- L -rhamnosidase, has demonstrated an α-(1→4) linkage between this trisaccharide and the remainder of the SII molecule. Carboxyl-reduced SII, , containing D -glucose (49.7%) and L -rhamnose (49.8%) has been prepared by reduction of the 2-hydroxyethyl ester in two stages. A comparison of the cleaved products of the action of specific, induced α- and β- D -glucosidases on SII and carboxyl-reduced SII demonstrated the presence of O -β-( D -glucopyranosyluronic acid)-(I→4)- O -α- D -glucopyranosyl-(1→4) residues in SII and O -β- D -glucopyranosyl-(1→4)- O -α- D -glucopyranosyl-(1→4) residues in the reduced polysaccharide. A possible repeating unit for SII is discussed.

A new method for quantitative, microscale determination of the sulphate content of carbohydrates

Abstract A novel method is described for the accurate, quantitative determination of sulphate on a micro-scale by using flame photometry. The effects of various classes of carbohydrates, amino acids, and inorganic ions on the method have been investigated. The method has been successfully applied to the determination of the sulphate ester content of sulphated carbohydrates, and a standard procedure has been established for a scale of 0–30 μg of sulphate.