D-Galactose 6-phosphate: anomeric distribution and analysis of its synthesis from D-galactose and polyphosphoric acid

D-Galactose 6-phosphate as synthesized by direct phosphorylation of D-galactose with polyphosphoric acid is contaminated with two of its positional isomers. These were separated from D-galactose 6-phosphate and from each other, and identified as D-galactose 3- and 5-phosphate by enzymic, chromatographic, and mass-spectral analysis. The previous misidentification of these isomers as furanose forms of D-galactose 6-phosphate has led to erroneous reports concerning the anomeric distribution of D-galactose 6-phosphate. The anomeric distribution of D-galactose 6-phosphate in a purified preparation was determined by gas-liquid chromatography and ¹³C-n.m.r. spectroscopy to be 32% α-pyranose, 64% β-pyranose, and no more than 4% furanose anomers.     

Selenium derivatives of L-arabinose, D-ribose,and D-xylose

Attempted cyclization of 2,3,4-tri-O-methyl-5-seleno-L-arabinose dimethyl acetal in acidic solution gave the corresponding diselenide. Intramolecular attack by the selenobenzyl group at C-5 of 5-O-p-tolylsulfonyl-L-arabinose dibenzyl diseleno-acetal resulted in the formation of benzyl 1,5-diseleno-L-arabinopyranoside. Similarly, 2,3,5-tri-O-methyl-4-O-p-tolylsulfonyl-D-xylose dibenzyl diselenoacetal gave benzyl 2,3,5-tri-O-methyl-1,4-diseleno-L-arabinofuranoside, and 2,3,4-tri-O-acetyl-5-O-p-tolylsulfonyl-D-xylose (or ribose) dibenzyl diselenoacetal gave benzyl 2,3,4-tri-O-acetyl-1,5-diseleno-D-xylo- (or ribo-)pyranoside. The glycosylic benzylseleno group was removed from the pyranoside with mercuric acetate, but attempted deacetylation of the product led to decomposition and not to the expected 5-seleno-D-xylopyranose.     

Proton magnetic resonance spectra of D-gluco-oligosaccharides and D-glucans

The p.m.r. spectra of some D-gluco-oligosaccharides and D-glucans in deuterium oxide were studied with respect to the anomeric proton. In (1→2)-linked glucobioses, the effect of change in configuration of the hydroxyl group at C-1 on the chemical shifts of the glycosidic proton is noted. Equilibrium mixtures of (1→2)-linked glucobioses contained more α-anomer than did the other examples, despite the cis configuration of substituents at C-1 and C-2. Some D-glucans were investigated with regard to the degree of branching, although solubility was a limitation.     

Metabolism of 14C-labelled D-glucose, D-fructose and allitol by Itea plants

The metabolism of D-[1-¹⁴C]glucose, D-[6-¹⁴C]glucose, D-[1-¹⁴C]fructose and D-[6-¹⁴C]fructose by leafy spurs of Itea plants results in rapid incorporation of label into allitol and D-allulose. The patterns of labelling found in the allitol and D-allulose are discussed, a direct interconversion from D-glucose and D-fructose being indicated. Allitol has been found to be an active metabolite in Itea plants.     

Nature of the uptake of d-galactose, d-glucose and α-methyl-d-glucoside by Saccharomyces cerevisiae

Both glucose-grown baker's yeast after induction and galactose-grown yeast appear to take up d-galactose by a system not requiring phosphorylation and only up to a diffusion equilibrium, as shown by pulse labelling, sampling at very short intervals and chromatographic analysis of extracts. Part of the sugar taken up is transformed into trehalose which is present in substantially greater amounts in cells than the transported sugar itself. The effect of 2,4-dinitrophenol and of iodoacetamide, as well as the nature of the efflux of sugars from preloaded cells, support the results. d-Glucose and α-methylglucoside are also taken up without phosphorylation.     

Synthesis of 3-O Substituted D-Mannoses

1,2,4,6-Tetra-O-acetyl-3-O-benzyl-α-D-mannopyranose (7) was obtained in good yield from 3,4,6-tri-O-benzyl-1,2-O-(1-methoxyethylidene)-β-D-mannopyranose (1) by acetolysis. Hydrogenolysis of 7 afforded 1,2,4,6-tetra-O-acetyl-α-D-mannopyranose which is a versatile intermediate for the preparation of other 3-O-substituted D-mannoses, such as 3-O-methyl-D-mannose and 3-O-α-D-mannopyranosyl-D-mannose. 3,4-Di-O-methyl-D-mannose was readily prepared from 1,2,6-tri-O-acetyl-3,4-di-O-benzyl-α-D-mannopyranose, which was also obtained from 1 by controlled acetolysis.     

6-thio- and -seleno-D-galactose esters of dimethylarsinous acid

The syntheses of 1,2:3,4-di-O-isopropylidene-6-S-dimethylarsino-6-thio-α-D-galactopyranose (2), methyl 6-S-dimethylarsino-6-thio-D-galactopyranoside (3), and 1,2:3,4-di-O-isopropylidene-6-Se-dimethylarsino-6-seleno-α-D-galactopyranose (8) are reported. The attempted preparation of 6-Se-dimethylarsino-6-seleno-D-galactopyranose (9) is also discussed. The n.m.r. spectra of these compounds are unexceptional, except for the slight downfield shift of the arsenic methyl resonances for the selenium compound as compared to the sulfur compound, confirming previous observations. The mass spectra of these compounds showed molecular ions for 2, 3, and 8. The u.v. spectra of the X-As (X = S, Se) chromophore are discussed in terms of a simplified MO model. 1,2:3,4-Di-O-isopropylidene-6-S-dimethylarsino-6-thio-α-D-galactopyranose (2) showed carcinostatic activity in the P388 system (mouse lymphocytic leukemia).     

Synthesis of 2,5,6- and 3,5,6-tri-O-methyl-D-galactose

Starting from methyl β-D-galactofuranoside, 3,5,6-tri-O-methyl-D-galactose (9) and 2,5,6-tri-O-methyl-D-galactose (16) were synthesized. The alditol acetates were prepared from 9 and 16, and their behavior in g.l.c. was compared. Mass spectra of the alditol acetates from 9 and 16 showed that these compounds gave fragmentations as expected. The alditol acetate from 16 was also prepared by an alternative route.     

Active transport of l-sorbose and 2-deoxy-d-galactose in Saccharomyces fragilis

Sorbose and 2-deoxy-d-galactose are taken up in Saccharomyces fragilis by an active transport mechanism, as indicated by the energy requirement of the process and the accumulation of free sugar against the concentration gradient. There are no indications for transport-associated phosphorylation as mechanism of energy coupling with these two sugars.The measured sugar-proton cotransport and the influx inhibition by uncouplers suggest a chemiosmotic coupling mechanism. Thus there are at least two different active transport mechanisms operative in Saccharomyces fragilis: transport-associated phosphorylation in the case of 2-deoxy-d-galactose and chemiosmotic coupling in the case of sorbose and 2-deoxy-d-galactose. The difference between the two mechanisms are discussed.Uncouplers do not stimulate downhill sorbose transport in energy-depleted cells and evoke an almost complete inhibition of efflux and of exchange transport.The differences between this sugar-proton cotransport system and similar systems in bacteria and Chlorella are discussed.     

Enzymic determination of d-galactose, d-arabinose,and their homologs

The enzymes d-galactose dehydrogenase and d-arabinose dehydrogenase were demonstrated to be applicable to the quantitative determination of d-galactose (and homologs) and d-arabinose (and homologs), respectively. The enzymic reactions were quite specific. When coupled with β-galactosidase, d-galactose dehydrogenase could be used in the quantitative determination of β-galactosides.     

The origin of the periodate-resistant D-glucose residues in starches and glycogens

Under ordinary analytical conditions, the proportion of periodate-resistant-D-glucose residues in starches and glycogens was consistently about one-third of the proportion of branching points. The resistant D-glucose residues became freely oxidisable after the limit-oxidised glucans had been reduced with sodium borohydride. The results can be explained by assuming that, when a D-glucose residue carrying a branch at position 6 is oxidised, the resulting two aldehyde groups both form 6-membered hemiacetal rings with the closest hydroxyl groups on neighbouring, unoxidised residues in the same, (1→4)-linked chain, whereas when the other D-glucose residues are oxidised, only one of the aldehyde groups shows a strong tendency to form a hemiacetal of this kind. It is suggested that, in the unbranched units, the other aldehyde group preferentially forms a hemiacetal with the primary hydroxyl group in the same unit.     

α-D-mannosidase and α-D-galactosidase from protein bodies of Lupinus angustifolius cotyledons

Two forms of p-nitrophenyl α-D-mannosidase and p-nitrophenyl α-D-galactosidase were purified from the protein bodies of mature Lupinus angustifolius seeds. A MW of 300 000 was calculated for both α-mannosidase A and B with K_m = 1.92 and 2.70 mM and activation energies of 10.9 and 10.8 kcal/mol, respectively. α-Galactosidase I and II had MWs of 70800 and 17000 with K_m = 0.282 and 0.556 mM and activation energies 17.7 and 11.5 kcal/mol, respectively. The enzymes had acid pH optima and were inhibited by various metal ions, carbohydrates and glycoproteins. They were able to release free sugar from several putative natural substrate oligosaccharides and the Lupinus storage glycoprotein, α-conglutin.     

Determination of l-galactose in polysaccharide material

A method is described for the identification and quantitative determination Of l-galactose in hydrolyzates of polysaccharide material. In this technique, all the d-galactose is oxidized to d-galactonic acid using the enzyme d-galactose dehydrogenase. Remaining sugars, including any l-galactose, are converted to their trimethylsilyl derivatives and estimated by GLC. l-Galactose was detected in polysaccharides of flax seed, corn cob and corn root, and in the cell wall of Acer pseudoplatanus suspension cultures. It is suggested that the sugar may be relatively widespread in plants.     

Synthesis of D-ristosamine and its derivatives

A convenient preparative route involving eleven steps starting from D-glucose is described for the synthesis of D-ristosamine (15) hydrochloride. Methyl 2-deoxy-β-D-arabino-hexopyranoside, prepared from 3,4,6-tri-O-acetyl-1,5-anhydro-2-deoxy-D-arabino-hex- 1-enitol, was benzylidenated, and the product mesylated to give methyl 4,6-O-benzylidene-2-deoxy-3-O-methylsulfonyl-β-D-arabino-hexopyranoside. Azidolysis of this compound and subsequent opening of the 1,3-dioxane ring with N-bromosuccinimide gave methyl 3-azido-4-O-benzoyl-6-bromo-2,3,6-trideoxy-βD-ribo-hexopyranoside. Simultaneous reduction of the azido and bromo groups gave a mixture that was benzoylated to give methyl N,O-dibenzoyl-β-D-ristosaminide and then hydrolyzed to 15 hydrochloride (3-amino-2,3,6-trideoxy-D-ribo-hexopyranose hydrochloride).     

Preparation of some acylated D-arabino-hexopyranosuloses and 4-deoxy-D-glycero-hex-3-enopyranosuloses

Oxidation of 1,3,4,6-tetra-O-benzoyl-α- and β-D-glucopyranose gave the tetra-O-benzoyl-α- and -β-D-arabino-hexopyranosuloses (3α and β), from which benzoic acid was readily eliminated to give the anomeric tri-O-benzoyl-4-deoxy-D-glycero-hex-3-enopyranosuloses (4α and β). The anomeric 1-O-acetyl-tri-O-benzoyl-D-arabino-hexopyranosuloses (7α and β) were obtained as very unstable syrups which readily lost benzoic acid. Treatment of tetra-O-benzoyl-2-O-benzyl-D-glucopyranose (1) with hydrogen bromide gave 3,4,6-tri-O-benzoyl-α-D-glucopyranosyl bromide (5) in one step.     

Purification and properties of D-3-hydroxybutyrate dehydrogenase from Paracoccus denitrificans

D-3-Hydroxybutyrate dehydrogenase from Paracoccus denitrificans has been purified to near homogeneity. The enzyme was prepared using DEAE-cellulose chromatography, affinity chromatography on immobilized Cibacron blue (Matrex Gel Blue A) and gel permeation chromatography. The pure enzyme was obtained by chromatofocusing as the final isolation step. The purification procedure yielded the enzyme with a specific activity of about 100 units/mg protein. The enzyme is specific for D-3-hydroxybutyrate and NAD and it exhibits anomalous kinetics (hysteresis) at low enzyme and coenzyme concentrations. It is relatively stable in the presence of EDTA at pH 7–8 higer salt concentrations. D-3-Hydroxybutyrate dehydrogenase is a tetramer with a molecular weight of 130 000 ± 10 000, its isoelectric point equals 5.10 ± 0.05. The enzyme is applicable to the determination of acetoacetate and D-3-hydroxybutyrate concentrations.     

Glycans from streptococcal cell-walls: the molecular structure of an antigenic diheteroglycan of D-glucose and L-rhamnose from Streptococcus bovis

The monosaccharide sequence and glycosidic bond-types have been determined for an antigenic diheteroglycan of D-glucose and L-rhamnose from the cell wall of Streptococcus bovis, strain C3, by use of an integrated analytical scheme based on methylation analysis, periodate oxidation, oxidation with chromium trioxide, enzymic hydrolysis, and chemical degradation. A typical molecule of the glycan consists of a main chain of L-rhamnosyl residues and isomaltose side-chains, with 16 repetitions of the structure, -α-L-rhamnosyl-(1→3)-[α-D)-glucosyl-(1→6)-α-D-glucosyl-(1→2)]-α-L-rhamnosyl-(1→2)-α-L-rhamnosyl-, linked alternately by α-L-(1→3) and α-L-(1→2) linkages. The isomaltose side-chains of the glycan are the immunodeterminant groups. The new antigenic glycan is ideally suited for use in the preparation of anti-isomaltose antibodies, which should be of value in the detection of other antigens having isomaltose determinants.     

Synthesis and growth regulator activity of fatty acyl derivatives of d-glucose and d-galactose

In an attempt to gain information about one or more components of the brassin complex, fatty acid esters of d-glucose and d-galactose were prepared and tested for growth regulator activity in a bean hypocotyl bioassay. 4-O-Acyl-d-glucoses and, perhaps, 1-O-acyl- d-galactoses had a similar qualitative activity to that of the brassin complex. 3-O-Acyl- d-galactoses inhibited elongation of bean hypocotyls and stimulated rooting. 3- And 6-O- acyl-d-glucoses both stimulated and inhibited elongation, depending on the source of fatty acids; in both cases, stimulation was observed when safflower oil was used as the source of fatty acids and inhibition was observed when peanut oil was used as the source of fatty acids. Fatty alkyl β-d-galactopyranosides were inactive.