Naoki Kashimura

Oxidation of carbohydrates with methyl sulfoxide containing phosphorus pentaoxide : I. Synthesis of some aldosuloses and aldosiduloses

Abstract Methyl sulfoxide containing phosphorus pentaoxide oxidizes secondary alcohol groups of carbohydrates to ketones. Oxidation proceeds most efficiently with N,N-dimethylformamide as solvent and with 3–4 molar equivalents of methyl sulfoxide and 1.5–2.0 molar equivalents of phosphorus pentaoxide. The following carbohydrates were oxidized to afford the corresponding aldosuloses and aldosiduloses in good or moderate yields: methyl4,6- O -benzylidene-2- O -( p -tolylsulfonyl)-α- D -gluco- and allo-pyranoside ( 1 and 18 ), methyl 2-acetamido-4,6- O -benzylidene-2-deoxy-α- D -gluco- and -allo-pyranoside ( 3 and 19 ), 1,2:5,6-di- O -isopropylidene-α- D -glucofuranose (6),1,2- O- isopropylidene-5- O -( p -tolylsulfonyl)-α- D -xylo- and -ribo-furanose ( 11 and 13 ), 1,2- O -isopropylidene-5- O -(di- O -phenylphosphono)-α- D -xylofuranose ( 14 ), and 1,2- O -isopropylidene-α- D -glucofuranurono-6,3-lactone ( 16 ).

Infrared spectra of the sulfonic esters of monosaccharides

Abstract The orientation of sulfonyloxy groups at different carbon atoms of the pyranose ring of monosaccharides has been examined by analysis of infrared spectra in the 800–900 cm −1 region, with particular reference to axial and equatorial orientations of the sulfonyloxy groups. Axial sulfonyloxy groups show a strong absorption band at 880–890 cm −1 , whereas equatorial ones absorb at 840–850 cm −1 . The absorption frequency is not affected by variations in the kind of hexopyranose, by the kind and position of the sulfonyloxy groups on the pyranose ring, or by the kind of phase used for the measurement.

Polysaccharide synthesis from mono- and oligo-saccharides by the action of phosphorus pentoxide in dimethyl sulphoxide

Abstract Phosphorus pentoxide-dimethyl sulphoxide (P 4 O 10 -DMSO) was found predominantly to catalyse the polymerization reaction of carbohydrates at below 35°C and the oxidation reaction at 60–65°C. A series of new synthetic polysaccharides were prepared from mono- and oligo-saccharides including 2-acetamido-2-deoxy- d -glucose and hexuronic acids in up to 48% yield by the action of P 4 O 10 -DMSO at 10–25°C. These synthetic polysaccharides showed s 20,w 0.68–1.34S, and the degree of polymerization fell in 15.3–4.7 monosaccharide units per polysaccharide chain on the basis of reducing end-group assay. A structural analysis by the methylation of the synthetic glucan (2) revealed α-1,4- and α-1,6-glucosidic linkages as main chains with various branchings. The synthetic polysaccharides contained 1.3–15.9% phosphorus, but the linkages are unknown.

Studies on pig serum lipoproteins. III. Affinity chromatography of native lipoproteins on concanavalin A-sepharose.

The comparison of the binding capacities of the three major classes of pig serum lipoproteins, very low-density, low-density and high-density lipoproteins, to concanavalin A, was demonstrated by affinity chromatography on concanavalin A-Sepharose. Very low-density lipoprotein was separated into two fractions (60 to 66% of total protein was adsorbed). Each fraction had different electrophoretic mobility in pore size gradient gel. The majority of the carbohydrate was found in the adsorbed fraction. The carbohydrate content of the unadsorbed fraction was 0.14% sialic acid. 0.47% hexosamine and 0.93% neutral sugars, and of the adsorbed fraction, 2.05, 3.21 and 4.20%, respectively. The adsorbed and unadsorbed fractions contained fucose, mannose and galactose in the molar ratio of 1.0 : 3.6 +/- 0.2 : 2.2 +/- 0.4 and 1.0 : 3.1 +/- 0.2 : 2.5 +/- 0.3, respectively. Based on these results, two different molecular species were proved to be present in very low-density lipoproteins. In high-density lipoproteins, 80 to 85% of the total protein was not adsorbed on concanavalin A-Sepharose in spite of the presence of mannose in the apoprotein. In contrast to these lipoproteins, low-density lipoprotein was completely adsorbed on concanavalin A-Sepharose. However, the separation of the subfractions of low-density lipoprotein as well as the subfractions of high-density lipoprotein could not be achieved by this affinity column. The carbohydrate content of eluted fractions of low-density and high-density lipoproteins was identical with the previously reported values obtained in native lipoproteins. This difference in affinities for concanavalin A was also evidenced by gel electrophoretic profiles in urea and in sodium dodecyl sulfate which showed different glycoprotein distribution in each class of lipoproteins.

A new convenient column for gel electrophoresis, isoelectric focusing, and zonal electrophoresis

Abstract A simple preparative electrophoresis column that can be utilized for gel and zonal electrophoresis and isoelectric focusing has been constructed.

Oxidation of Carbohydrates with Dimethyl Sulfoxide–Phosphorus Pentaoxide

Publisher Summary This chapter discusses the oxidation of carbohydrates with dimethyl sulfoxide–phosphorus pentaoxide. The oxidation of isolated secondary alcoholic groups of carbohydrates is usually performed by treating one mole of the reactant with 3–4 moles of dimethyl sulfoxide (DMSO) and 1–1.5 moles of phosphorus pentaoxide in N,N-dimethylformamide (DMF) for 1.5–2.0 hours at 65°–70°. In a study described in the chapter, the protective groups and linkages commonly used in carbohydrate chemistry were investigated for stability to the oxidant. It was found that sulfonyloxy, acetoxy, benzoyloxy, isopropylidene, benzylidene, ethylidene, methoxyl, triphenylmethoxyl, nitrate and acetamido groups, and glycosidic bonds involving nucleosidic, phenolic, alkyl, and thioacetal substituents were stable toward the oxidant.