Search

The uptake of glucose, fructose, and allose by Neurospora was shown to be energy-dependent, to follow Michaelis-Menten kinetics, and to display competition in certain combinations. Neurospora was shown to be unable to transport sucrose into cells. After hydrolysis of the disaccharide by transmembrane invertase, only the glucose moiety enters the cell at a significant rate. The possibility was tested that invertase releases product (s) in an oriented fashion that favors transport into the cell. The experimental results do not strongly support this possibility. Results roughly similar to those given by sucrose were obtained by use of the artificial substrate allosucrose; in the latter case, a weakly oriented release of products may have been detected.

The transport of some monosaccharides into renal tubular cells was investigated using slices of rabbit kidney cortex: 1. 1. An active, Na + -dependent and phlorrhizin-sensitive cellular accumulation of β-methyl- d -glucoside, d -glucosamine and d -galactosamine was demonstrated. d -Mannitol, d -glucose, N- acetyl- d -glucosamine , 3-deoxy- d -glucose, d -allose, d -ribose and 2,6-dideoxy- d -altrose were not actively accumulated against their concentration gradients. 2-Deoxy- d -allose, 2-deoxy- d -ribose and possibly 2-deoxy- d -xylose were transported against a small concentration gradient by a Na + -independent mechanism. A comparison of the transport properties of 26 monosaccharides indicates the following structural requirements for active transport: a hemiacetal group, C-3-OH (in a configuration identical with that of d -glucose) and C-6-OH. The Na + requirement for active transport is related to the presence of a hydrophilic (-OH or -NH 2 ) group on C-2. 2. 2. The apparent kinetic parameters, K m and v max , are given for the active transport of a α-methyl- d -glucoside, d -galactose, 2-deoxy- d -glucose and 2-deoxy- d -galactose into renal tubular cells. The values of the apparent transport K m for these sugars varied only slightly between 0.79 ± 0.07 for d -galactose to 3.0 ± 0.11 for 2-deoxy- d -galactose; rather wide variations of v max were found (12 μmoles per g cell water per h for 2-deoxy- d -glucose to 62 ± 4.7 for α-methyl- d -glucoside). 3. 3. The competition for transport between a variety of monosaccharides was investigated: the found K i was within the range of independently determined K m for the inhibition of galactose of 2-deoxy- d -galactose and 2-deoxy- d -glucose transport. However, the K i for the inhibition of d -galactose transport by 2-deoxy- d -galactose was one order of magnitude higher than the K m of the latter sugar. Similarly, no agreement between the respective K i and K m was found for the competitive inhibition between α-methyl- d -glucoside and galactose. d -Glucose, which competitively inhibited the transport of 2-deoxy- d -glucose, had practically no effect on the transport of 2-deoxy- d -galactose even at a molar ratio of 1:50. 4. 4. These kinetic data indicate the existence of several pathways for the active sugar transport into renal tubular cells. 5. 5. A correlation between the reabsorption of sugars in the kidney tubule ( in vivo ) and their active cellular accumulation ( in vitro ) is demonstrated.

The reaction of osmic acid with 1,6-anhydro-3,4-dideoxy-β-DL-erythro-hex-3-enopyranose and its 2-O-methyl and 2-O-acetyl derivatives in either pyridine or dioxane solution has produced 1,6-anhydro-β-DL-allopyranose and 1,6-anhydro-β-DL-galactopyranose and the corresponding 2-O-methyl and 2-O-acetyl derivatives. These or their fully acetylated derivatives could be hydrolyzed to α,β-DL-allose and α,β-DL-galactose and the 2-O-methyl derivatives. The proportion of allo to galacto product obtained varies widely with the solvent used in hydroxylation, showing that attack by osmic acid is subject to steric control.

2-Deoxy-2-fluoro- D -altrose and 3-deoxy-3-fluoro- D -glucose have been prepared by treatment of methylated or acetylated methyl 2,3-anhydro-α- D -allopyranoside with hydrogen tetrafluoridoborate in hydrogen fluoride. Epimerisation of 2-deoxy-2-fluoro- D -altrose yielded the corresponding D -allose derivative.

Acetonation of D -allose in the presence of sulfuric acid gives 2,3:5,6-di- O -isopropylidene-β- D -allofuranose ( 4 ) in good yield. Oxidation of 4 with methyl sulfoxide and acetic anhydride gave 2,3:5,6-di- O -isopropylidene- D -allono-1,4-lactone (7). Compound 4 was also obtained from 1,2:5,6-di- O isopropylidene-α- D -allofuranose ( 1 ) in one step by an acetal-migration reaction. The acetonation of D - ribo -hexulose ( D -psicose) in the presence of anhydrous copper sulfate and sulfuric acid has been re-examined, and the main product has been shown to be 1,2:3,4-di- O -isopropylidene- D -psicofuranose ( 12 ), by conversion of 12 into 6-deoxy- D -psicose ( 16 ) through 1,2:3,4-di- O isopropylidene-6- O-p -tolylsulfonyl- D -psicofuranose ( 14 ).

Starting from methyl 2,4,6-tri-O-benzyl-α-D-glucopyranoside, a facile synthesis of 3-amino-3-deoxy-D-allose was carried out; some new O-benzyl derivatives of 3-amino-3-deoxy-D-allopyranose are also described.

Thiolacetate, benzyl mercaptide and acetate ions in dimethylformamide caused displacements of the 3-O-mesyl group in I and analogous compounds affording derivatives of 2-amino-2-deoxy- d -allose and/or 2-amino-2-deoxy- d -2-deoxy- d -glucose, the structures of which have been proved. 2-Amino-2,3-dideoxy- d -glucose has been prepared for the first time.

Intestinal absorption of sixteen carbohydrates was studied using cannulated intestinal segments of rats. The carbohydrates studied included all of the d -aldo-hexoses and d -aldopentoses as well as l -xylose, l -arabinose, d -glucosamine and N- acetyl - d - glucosamine . Of these, only d -glucose, d -galactose, and d -allose were rapidly absorbed.

This report deals with the application of methyl-β-D-glucoside as a more satisfactory internal standard in using gas-liquid chromatography (GLC) of monosaccharides-derived alditolacetates when performing quantitative analysis on monosaccharides. Rhamnose and myoinositol is currently and widely used as an internal standard for quantitative GLC. However, the former is affected a great deal by tailing of solvents and acetylation reagents; while the latter requires an inconveniently long retention time. Moreover, both are normally found in the plant kingdom, for example in agricultural wastes and hence are not suitable for use as a standard. Other sugars such as allose and idose although they are recommended by some authors, are not readily available in reasonable quantities. Among all sugars and sugar derivatives tested in this study, methyl-β-D-glucoside was found to be the most satisfactory internal standard, since it appears midway on the chromatogram between D-xylose and D-mannose. An advantage of using this glucoside is that it is stable and commercially available in the reagent grade quality. Moreover, chromatographic peak height ratios (monosaccharide/internal standard) is exactly proportional with regards to the weight ratios (monosaccharide/internal standard), and the glucoside is not normally found in the hydrolysates of the plant kingdom's natural raw materials.

By means of 13 C and 1 H NMR spectroscopy three flavone glycosides, obtained from Stachys recta , were identified as 7- O -(2″- O -6″′- O -acetyl-β- D -allopyranosyl-β- D -glucopyranosides) of 4′- O -methylisoscutellarein, isoscutellarein and 3′-hydroxy-4′- O -methylisoscutellarein. The latter two compounds are isolated for the first time. Only mannose and glucose have been reported previously as sugar components of flavonoids of the genus Stachys .

A novel flavone glycoside has been obtained from the whole plant of Veronica filiformis and identified by means of 13 C NMR spectroscopy as isoscutellarein 4′-methyl ether 7- O -β-(6‴- O -acetyl-2″- O -allosylglucoside). The related isoscutellarein glycoside is also present. This is the first report of 2-allosylglucose as a disaccharide unit of flavonoids. 13 `C NMR data on some A-ring trioxygenated flavonoids are also presented.

Cristallisation dans P2 1 2 1 2 1 avec Z=4; affinement jusqu'a R=0,029. La molecule a la conformation chaise pyrannose 4 C 1 . Le groupe hydroxymethyl a la conformation gauche-gauche. Chaque molecule est entouree par huit molecules apparentees par symetrie par des liaisons hydrogene. De facon tres inhabituelle, l'atome O anomere est deux fois accepteur de liaison hydrogene

Ten 3-substituted D-glucose and D-allose derivatives were tested for their ability to inhibit growth of Botrytis cinerea. The results obtained indicate the importance of oxygen at position 3 for inhibitory activity. 3-Fluoro-3-deoxy-D-glucose was the most inhibitory analogue.

On reaction of 1,2:5,6-di-O-isopropylidenc-3-O-(p-tolylsulfonyl)-α-D-glueofuranose (1) with hydrazine hydrate at 140° besides formation of 3-deoxy-3-hydrazino-1,2:5,6-di-O-isopropylidene-α-D-allofuranose (2) and 3-dcoxy-1,2:5,6-di-O-isopropylidene-α-D-erythro-hex-3-enofuranose (3), ring transformation into 3-[4′-(2′,2′-dimethyl-1′,3′-dioxolanyl)]pyridazine (4) takes place. At 170°, however, only 2 and 4 are formed, indicating that 3 is the precursor of 4. Treatment of 3 with hydrazine hydrate at 170° indeed gives a nearly quantitative ring expansion into 4. Treatment of 3-dcoxy-3-hydrazino-1,2:5,6-di-O-isopropylidenc-α-D-glucofuranose (8) as well as the stereoisomeric allofuranose 2 with concentrated hydrochloric acid gives a nearly quantitative ring interconversion into 3-(D-erythro-trihydroxypropyl)pyrazole (9).

The rates of these reactions in dimethylformamide, monitored by 1H n.m.r. spectroscopy, have been measured for derivatives of gulose, allose, glucose, and galactose, and found to decrease in that order. From the reactions with the derivatives of gulose, allose, and glucose, 3-S-benzoyl-1,2:5,6-di-O-isopropylidene-3-thio-α-D-galactose, -glucose, and -allose, respectively, were isolated, and their 1H n.m.r. spectra are recorded.

By studying the energy-requiring control of the hexose transport system (the transport "curb") in a lung fibroblast mutant called the phosphoglucose isomerase mutant (because it is devoid of the enzyme phosphoglucose isomerase) the following features were noted. The aldohexose D-allose, if added over 20 hr to a culture of the mutant, promotes the development of an intense curb of the hexose transport system, greatly surpassing that brought about by incubation with glucose. The allose-mediated curb can be circumvented by various metabolic inhibitors as well as by the presence of other aldohexoses such as mannose.

The Chemotaxis of Salmonella typhimurium LT2-ST1, grown with different sole carbon sources toward ribose, allose, serine, aspartate, and glucose, was examined. Maximum Chemotaxis toward serine, aspartate, and glucose were unchanged with either glucose or citrate as the carbon source. The height of the peak in the ribose response curve was 25% of a standard serine response when the bacteria were grown on citrate. However, when the bacteria were grown on glucose, the ribose response was 1% of the serine standard, and when on glycerol, 5%. Chemotaxis toward allose, a competitive inhibitor of ribose Chemotaxis, was similarly affected. The amount of ribose binding protein, the receptor for ribose Chemotaxis, was determined in bacteria grown on citrate, glucose, or glycerol. The amount of ribose-binding protein released from cells grown on glucose or glycerol was appreciably less than the amount released from cells grown on citrate. These data suggest that the observed effect on ribose Chemotaxis is due to catabolite repression of ribose-binding protein and another component of the chemotactic system.

5-Thio-D-glucose (9) reacts with acetone in the presence of an acid catalyst to give 1,2-O-5,6-S,O-di-isopropylidene-5-thio-α-D-glucofuranose (10). 5-Thio-D-altrose (37) similarly gives a 1,2 : 5,6-diacetal (39) but 5-thio-D-allose (27) affords 2,3-O-5,6-S,O-di-isopropylidene-5-thio-β-D-allofuranose (28). Under kinetic conditions, using 2,2-dimethoxypropane, the major products from 5-thio-D-glucose (9) and 5-thio-D-allose (27) are 2,3 : 4,6-di-O-isopropylidene-5-thin-D-gluco- and allopyranoses (11a) and (32), even though the former possesses a trans-fused dioxolane ring. 1,2 : 4,6-Di-O-isopropylidene-5-thio-α-D-glucopyranose (14), which is also produced in the former reaction, has been synthesised by an alternative route. 2,2-Dimethoxypropane and acetone react with methyl 5-thio-α- or β-D-glucopyranosides (3) or the related methyl 5-thio-α- or β-D-allopyranosides (25), to give the 2,3 : 4,6-diacetals (5) and (26) respectively. With acetone alone, the glucosides (3) give mainly the 4,6-monoacetals (4) together with smaller amounts of the 2,3 : 4,6- diacetals (5); the allosides (25) give complex mixtures and methyl 5-thio-α-D-altropyranoside (40) gives first the 4,6-acetal (41) which then isomerises into the 3,4-acetal (42). Methylation of either of the pyranose 2,3 : 4,6-diacetals (11a) or (32) leads to the corresponding 2,3 : 4,6-di-O-isopropylidene-5-S-methyl-5-thio-aldehydo compounds (44) and (45), respectively.

Starting with the α-D-allofuranose (I), the anhydrofuranose (IVa) is prepared by rearrangement of the furanose (III) in the presence of tin(IV) chloride in methylene chloride.

2, 3-Dideoxy-2, 3-epithio-β-D-allofuranose (3c) and 2, 3-dideoxy-2, 3-epithio-α-D-mannofuranose (4c) were obtained, respectively, by the hydrolyses of methyl 2, 3-dideoxy-2, 3-epithio-α-D-allopyranoside (1a) and methyl 2, 3-dideoxy-2, 3-epithio-α-D-mannopyranoside (2a) with Amberlite CG-120 (H+) in H2O. The structures of these reducing sugars were confirmed by nuclear magnetic resonance spectroscopy.

The composition of the defence secretions of six species of chrysomelid beetles (Chrysolina polita, C. americana, C. grossa, C. herbacea, C. fastuosa, and Oreina gloriosa) belonging to the sub-tribe Chrysolinina has been investigated. Two known cardenolide aglycones, sarmentogenin (1) and oleandrigenin (23), and fourteen new cardiac glycosides (7–20) have been isolated and their structure established by spectral and chemical methods. Three of the glycosides (18, 19, and 20) are based on a new cardenolide aglycone, namely Δ11-digitoxigenin. All the new glycosides but 17 contain monosaccharides (e. g. lyxose, ribose, allose) which are rarely encountered in secondary metabolites. Ethanolamine was shown to be present in the secretions of the six species examined, as well as in C. hyperici and in C. coerulans. In the latter, ethanolamine is accompanied by its N-(γ-glutamyl) derivative.

The biosynthesis of the pyrimidine moiety and the uronic acid moiety of the polyoxins and the formation of unnatural polyoxins has been studied in Streptomyces cacaoi. Experimental evidence is provided for the biosynthesis of thymine via a pathway that is independent of thymidylate synthetase. This new thymine pathway is based on two experimental approaches. First, two known inhibitors of DNA synthesis (1-formylisoquinoline thiosemicarbazide and 5-fluoro-2′-deoxyuridine), when added to polyoxin-producing cultures of S. cacaoi, inhibit the synthesis of TMP from exogenously supplied uracil but do not inhibit the synthesis of the thymine or hydroxymethyluracil in the polyoxin complex. Second, exogenously supplied thymine and hydroxymethyluracil are taken up by S. cacaoi but are not incorporated into the thymine or hydroxymethyluracil of the polyoxin complex. The thymine is incorporated into the DNA. The uracil in polyoxin L could be the parent pyrimidine chromophore with C-1 additions occurring at carbon-5 to form thymine and hydroxymethyluracil. Carbon-3 of serine but not the methyl group of methionine is a one-carbon source for the formation of the thymine and hydroxymethyluracil in the polyoxin complex. S. cacaoi can synthesize unnatural polyoxins, as evidenced by the incorporation of 5-fluoro, 5-bromo, and 6-azauracil into the polyoxins; 5-iodo-, 2-thio-, or 4-thiouracil is not a substrate. Two new polyoxin analogs synthesized and characterized when 5-fluorouracil is added to the cultures are 5-fluoropolyoxin L and 5-fluoropolyoxin M. There is a marked change in the molar ratio of the uracil:thymine:hydroxymethyluracil chromophores in the polyoxin complex following the incorporation of 5-fluoro-, 5-bromo-, or 6-azauracil. Apparently, the unnatural polyoxins inhibit the addition of the C-1 unit to carbon-5 of uracil in the polyoxin complex. Polyoxin L and polyoxin C do not inhibit Escherichia coli and Streptococcus faecalis, but 5-fluoropolyoxin L and 5-fluoropolyoxin C inhibit both these organisms. There is little or no difference in the inhibition of the fluorinated and natural polyoxins against leukemia L-1210 cells. The fluoro group on carbon-5 of the uracil ring does not affect the enzyme-inhibition complex with chitin synthetase since the inhibition constant of fluoropolyoxins L is the same as has been reported for polyoxins A, D, and L. The 14C-labeling pattern in the 5′-amino-5′-deoxy- d -allofuranosyluronic acid moiety of the polyoxins from 14C-labeled glucose, allose, and glycerol suggests that the formation of this unique C-6 uronic acid in the polyoxins does not proceed via the direct oxidation of either d -glucose or d -allose to the -onic or -uronic acids. Glucose is converted to two three-carbon trioses, followed by either (i) the oxidation of one of the trioses to a threecarbon acid and subsequent condensation with another three-carbon sugar to form the C-6 uronic or (ii) an 80:20 equilibrium of the two trioses followed by condensation to a hexose which is then oxidized to the C-6 uronic acid.

The hexose transport in a hamster fibroblast mutant (DS7), unable to use glucose for generation of energy, is nevertheless subject to a marked down-regulation ("curb") after prolonged incubation of monolayer cultures with glucose; fructose is unable to exert any curb. D-Allose, an all-cis hexose, mediates a vigorous curb of the transport system. Moreover, prolonged coincubation of glucose or allose with tunicamycin (TM) brings about an additional effect that is not an inhibition of the transport system, which we shall call the "concerted" transport curb. This type of concerted transport curb requires L-glutamine in the maintenance medium; moreover, addition of cycloheximide prevents the development of this TM effect. Apparently, cellular protein synthesis or protein turnover or both are required for the development of the TM-concerted transport curb. The concerted transport curb can be reversed in sugar-free or in fructose-containing medium, even upon readdition of TM. In contrast, the sole readdition of glucose or D-allose renders the concerted curb irreversible. This raises the question of whether the cells under the condition of the concerted curb somehow have internalized the TM into the membrane.

Over 200 bacterial strains were selected for anaerobic growth at 50°C and extracellular polysaccharide production in a sucrose-mineral salts medium with NaNO 3 and up to 10% NaCl. The predominant cell type was an encapsulated gram-positive, motile, facultative sporeforming rod similar to Bacillus species. Strain SP018 grew and produced the polysaccharide on a variety of substrates at salinities up to 12% NaCl. Good polymer production only occurred anaerobically and was optimal between 4 and 10% NaCl. The ethanol-precipitated SP018 polymer was a charged heteropolysaccharide that contained glucose, mannose, arabinose, ribose, and low levels of allose and glucosamine. The SP018 polymer showed pseudoplastic behavior, was resistant to shearing, and had a higher viscosity at dilute concentrations and at elevated temperatures than xanthan gum. High-ionic-strength solutions reversibly decreased the viscosity of SP018 polymer solutions. The bacterium and the associated polymer have many properties that make them potentially useful for in situ microbially enhanced oil recovery processes.

The composition of the defence secretions of six species of chrysomelid beetles (Chrysolina polita, C. americana, C. grossa, C. herbacea, C. fastuosa, and Oreina gloriosa) belonging to the sub‐tribe Chrysolinina has been investigated. Two known cardenolide aglycones, sarmentogenin (1) and oleandrigenin (23), and fourteen new cardiac glycosides (7–20) have been isolated and their structure established by spectral and chemical methods. Three of the glycosides (18, 19, and 20) are based on a new cardenolide aglycone, namely Δ11‐digitoxigenin. All the new glycosides but 17 contain monosaccharides (e. g. lyxose, ribose, allose) which are rarely encountered in secondary metabolites. Ethanolamine was shown to be present in the secretions of the six species examined, as well as in C. hyperici and in C. coerulans. In the latter, ethanolamine is accompanied by its N‐(γ‐glutamyl) derivative. Copyright © 1988 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim, SCOPUS: ar.j, info:eu-repo/semantics/published