- THE STEREOSELECTIVE SYNTHESIS OF D-RIBULOSE
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In the presence of zinc halide, 2-furyllithium reacts with 2,3-O-isopropylidene-D-glyceraldehyde in a highly stereoselective manner to give the chiral and stereo-defined alcohol, 2,2-dimethyl-4-(2-furyl)hydroxymethyl-1,3-dioxolane, which is further elaborated to afford D-ribulose in three steps.
- Suzuki, Keisuke,Mukaiyama, Teruaki,Yuki, Yoichi
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- Characterization of a novel D-arabinose isomerase from Thermanaeromonas toyohensis and its application for the production of D-ribulose and L-fuculose
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D-Ribulose and L-fuculose are potentially valuable rare sugars useful for anticancer and antiviral drugs in the agriculture and medicine industries. These rare sugars are usually produced by chemical methods, which are generally expensive, complicated and do not meet the increasing demands. Furthermore, the isomerization of D-arabinose and L-fucose byDD-arabinose and L-fucose by D-arabinose isomerase from bacterial sources for the production of D-ribulose and L-fuculose have not yet become industrial due to the shortage of biocatalysts, resulting in poor yield and high cost of production. In this study, a thermostable D-ribulose- and L-fuculose producing D-arabinose isomerase from the bacterium Thermanaeromonas toyohensis was characterized. The recombinant D-arabinose isomerase from T. toyohensis (Thto-DaIase) was purified with a single band at 66 kDa using His-trap affinity chromatography. The native enzyme existed as a homotetramer with a molecular weight of 310 kDa, and the specific activities for both D-arabinose and L-fucose were observed to be 98.08 and 85.52 U mg?1, respectively. The thermostable recombinant Thto-DaIase was activated when 1 mM Mn2+ was added to the reactions at an optimum pH of 9.0 at 75 °C and showed approximately 50% activity for both D-arabinose and L-fucose at 75 °C after 10 h. The Michaelis-Menten constant (Km), the turnover number (kcat) and catalytic efficiency (kcat/Km) for D-arabinose/L-fucose were 111/81.24 mM, 18,466/10,688 min?1, and 166/132 mM?1 min?1, respectively. When the reaction reached to equilibrium, the conversion rates of D-ribulose from D-arabinose and L-fuculose from L-fucose were almost 27% (21 g L?1) and 24.88% (19.92 g L?1) from 80 g L?1 of D-arabinose and L-fucose, respectively.
- Iqbal, Muhammad Waheed,Riaz, Tahreem,Hassanin, Hinawi A.M.,Ni, Dawei,Mahmood Khan, Imran,Rehman, Abdur,Mahmood, Shahid,Adnan, Muhammad,Mu, Wanmeng
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- Production of keto-pentoses: Via isomerization of aldo-pentoses catalyzed by phosphates and recovery of products by anionic extraction
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Xylulose and ribulose are rare keto-pentoses which are in high demand for the synthesis of commodities and fine chemicals. The production of keto-pentoses via isomerization of aldo-pentoses presents a carbon-efficient synthetic method. However, the isomerizations are equilibrium processes with thermodynamically limited yields of the products. In this work we examined isomerization of aldo-pentoses into keto-pentoses in the presence of NaH2PO4 + Na2HPO4 as a soluble catalyst at pH 7.5. A reaction network was proposed based on product distribution with d-(1-13C)-ribose as a substrate. Additionally, kinetics of the isomerization reactions was addressed. Selectivity for the keto-pentoses dramatically depends on the structure of the substrate. Arabinose and xylose give rise to a number of isomeric pentoses with low selectivities for the target products. Investigation of the reaction kinetics suggests that xylose and arabinose slowly isomerize into xylulose and ribulose, respectively. The latter react further significantly quicker to produce a number of isomers as subsequent products. This causes a complex mixture of products with low selectivity for the keto-pentoses. In contrast, ribose and lyxose as substrates yield ribulose and xylulose with rather high selectivities of 68-79% at 20% conversion. Ribose and lyxose quickly isomerize into ribulose and xylulose, respectively, whereas the subsequent processes are relatively slow. This results in a high selectivity for the keto-pentoses based on ribose and lyxose. Moreover, the isolation of xylulose from the reaction mixture was also studied. Xylulose can be selectively recovered after the isomerization of lyxose using anionic extraction with o-hydroxymethyl phenylboronic acid (HMPBA). After extraction, the aqueous phase containing phosphates and remaining lyxose can be recycled. After four cycles, the yield of xylulose reached 37% though only 19% can be achieved under batch conditions. Xylulose can be further recovered from the organic phase by back extraction using an acidified solution. Ribulose can also be extracted as an anionic complex with HMPBA, though ribose is co-extracted in this case and a separation of ribulose from ribose cannot be achieved. Extraction of the keto-pentoses occurs due to formation of β-xylulose-HMPBA and α-ribulose-HMPBA anionic complexes, whose molecular structures were established by NMR and MS.
- Delidovich, Irina,Gyngazova, Maria S.,Sánchez-Bastardo, Nuria,Wohland, Julia P.,Hoppe, Corinna,Drabo, Peter
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p. 724 - 734
(2018/02/14)
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- Facile enzymatic synthesis of ketoses
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Studies of rare ketoses have been hampered by a lack of efficient preparation methods. A convenient, efficient, and cost-effective platform for the facile synthesis of ketoses is described. This method enables the preparation of difficult-to-access ketopentoses and ketohexoses from common and inexpensive starting materials with high yield and purity and without the need for a tedious isomer separation step. A spoonful of sugar: A convenient, efficient, and cost-effective platform for the facile synthesis of ketoses is described. This method, which involves a one-pot mulitenzyme (OPME) reaction, enables the preparation of rare ketopentoses and ketohexoses from common and inexpensive starting materials with high yield and purity and without the need for a tedious isomer separation step.
- Wen, Liuqing,Huang, Kenneth,Wei, Mohui,Meisner, Jeffrey,Liu, Yunpeng,Garner, Kristina,Zang, Lanlan,Wang, Xuan,Li, Xu,Fang, Junqiang,Zhang, Houcheng,Wang, Peng George
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supporting information
p. 12654 - 12658
(2015/10/28)
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- Selective electrocatalytic oxidation of sorbitol to fructose and sorbose
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A new electrocatalytic method for the selective electrochemical oxidation of sorbitol to fructose and sorbose is demonstrated by using a platinum electrode promoted by p-block metal atoms. By the studying a range of C4, C5 and C6 polyols, it is found that the promoter interferes with the stereochemistry of the polyol and thereby modifies its reactivity.
- Kwon, Youngkook,De Jong, Ed,Van Der Waal, Jan Kees,Koper, Marc T. M.
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p. 970 - 973
(2015/03/30)
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- Catalytic consequences of borate complexation and pH on the epimerization of l-arabinose to l-ribose in water catalyzed by Sn-Beta zeolite with borate salts
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Sn-Beta zeolite with sodium tetraborate cooperatively catalyzes the epimerization of aldoses via an intramolecular 1,2 carbon-shift mechanism. l-Arabinose is one of the seven common sugars and its epimer, l-ribose, is a valuable rare sugar with applications in antiviral and anticancer agents. Here, a full factorial experimental design is performed to demonstrate the catalytic consequences of varying key reaction parameters such as pH, borate to sugar ratio, and reaction time. Reactivity data revealed that isomerization is favored under acidic pH conditions (pH 7.8). Using a 5 wt% arabinose feed and 100:1 sugar-metal ratios at 343 K, conversions ranging from 20% to 30% were obtained with selectivities of 75%, 84%, and 91% for boron-sugar ratios of 0.2:1, 0.5:1, and 1:1, respectively. The predominance of epimerization over isomerization products with substoichiometric borate suggests that one borate can influence the reactivity of several sugar molecules and may influence the Sn active site directly. Reaction data obtained under differential conditions revealed that the epimerization reaction follows first order kinetics over a wide temperature range with an apparent activation energy of 98 kJ/mol and pre-exponential factor of 1.9 × 1014 L mol Sn-1 s-1.
- Gunther, William R.,Duong, Quynh,Román-Leshkov, Yuriy
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p. 294 - 302
(2013/11/06)
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- Molecular characterization of a thermostable l-fucose isomerase from Dictyoglomus turgidum that isomerizes l-fucose and d-arabinose
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A recombinant thermostable l-fucose isomerase from Dictyoglomus turgidum was purified with a specific activity of 93 U/mg by heat treatment and His-trap affinity chromatography. The native enzyme existed as a 410 kDa hexamer. The maximum activity for l-fucose isomerization was observed at pH 7.0 and 80 °C with a half-life of 5 h in the presence of 1 mM Mn2+ that was present one molecular per monomer. The isomerization activity of the enzyme with aldose substrates was highest for l-fucose (with a kcat of 15,500 min-1 and a Km of 72 mM), followed by d-arabinose, d-altrose, and l-galactose. The 15 putative active-site residues within 5 A of the substrate l-fucose in the homology model were individually replaced with other amino acids. The analysis of metal-binding capacities of these alanine-substituted variants revealed that Glu349, Asp373, and His539 were metal-binding residues, and His539 was the most influential residue for metal binding. The activities of all variants at 349 and 373 positions except for a dramatically decreased kcat of D373A were completely abolished, suggesting that Glu349 and Asp373 were catalytic residues. Alanine substitutions at Val131, Met197, Ile199, Gln314, Ser405, Tyr451, and Asn538 resulted in substantial increases in Km, suggesting that these amino acids are substrate-binding residues. Alanine substitutions at Arg30, Trp102, Asn404, Phe452, and Trp510 resulted in decreases in kcat, but had little effect on Km.
- Hong, Seung-Hye,Lim, Yu-Ri,Kim, Yeong-Su,Oh, Deok-Kun
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experimental part
p. 1926 - 1934
(2012/09/22)
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- Indium-mediated allenylation of aldehydes and its application in carbohydrate chemistry: Efficient synthesis of D -ribulose and 1-deoxy- D -ribulose
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A two-step reaction sequence starting with the indium-mediated allenylation of aldehydes with 4-bromo-2-butyn-1-ols and subsequent ozonolysis of the resulting allenylic product was developed to generate a variety of dihydroxyacetone derivatives. The regioselectivity of the indium-promoted C-C bond-forming reaction can be manipulated through hydroxy protecting groups on 4-bromo-2-butyn-1-ol, yielding either allenes or alkynes as preferred products. Compared to established protocols, the necessary amount of indium for this type of allenylation can be decreased by a factor of two to four. The versatility of this strategy was demonstrated in thestereoselective and straightforward synthesis of D-ribulose and 1-deoxy-D-ribulose. Copyright
- Fischer, Michael,Schmoelzer, Christoph,Nowikow, Christina,Schmid, Walther
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experimental part
p. 1645 - 1651
(2011/05/05)
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- Aldose-ketose interconversion in pyridine in the presence of aluminium oxide
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The reaction rate of the Lobry de Bruyn-Alberda van Ekenstein transformation of aldoses to ketoses in boiling pyridine was strongly increased by the addition of aluminium oxide. In addition to aldose-ketose transformation, 2-epimers of the starting aldoses and 3-epimers of the primarily produced ketoses were formed to some extent, as reported also when these reactions are carried out without aluminium oxide. The relative amounts of the primary ketose and the starting aldose in the reaction mixtures may be explained on the basis of their stability, predicted from reported free energy calculations. Isomerisation of ketoses to aldoses was much slower than the reverse reaction. The relative free energies are also in these cases important, the very stable xylo-2-hexulose gave only 7% and 6% of the aldoses gulose and idose, respectively, after boiling for 7 h in pyridine in the presence of aluminium oxide.
- Ekeberg, Dag,Morgenlie, Svein,Stenstrom, Yngve
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p. 1992 - 1997
(2008/02/10)
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- Prebiotic carbohydrate synthesis: Zinc-proline catalyzes direct aqueous aldol reactions of α-hydroxy aldehydes and ketones
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Zn-proline catalyzed aldolisation of glycoladehyde gave mainly tetroses whereas in the cross-aldolisation of glycoladehyde and rac-glyceraldehyde, pentoses accounted for 60% of the sugars formed with 20% of ribose. The Royal Society of Chemistry 2005.
- Kofoed, Jacob,Reymond, Jean-Louis,Darbre, Tamis
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p. 1850 - 1855
(2007/10/03)
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- Base catalysed isomerisation of aldoses of the arabino and lyxo series in the presence of aluminate
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Base-catalysed isomerisation of aldoses of the arabino and lyxo series in aluminate solution has been investigated. L-Arabinose and D-galactose give L-erythro-2-pentulose (L-ribulose) and D-lyxo-2-hexulose (D-tagatose), respectively, in good yields, whereas lower reactivity is observed for 6-deoxy-D-galactose (D-fucose). From D-lyxose, D-mannose and 6-deoxy-L-mannose (L-rhamnose) are obtained mixtures of ketoses and C-2 epimeric aldoses. Small amounts of the 3-epimers of the ketoses were also formed. 6-Deoxy-L-arabino-2-hexulose (6-deoxy-L-fructose) and 6-deoxy-L-glucose (L-quinovose) were formed in low yields from 6-deoxy-L-mannose and isolated as their O-isopropylidene derivatives. Explanations of the differences in reactivity and course of the reaction have been suggested on the basis of steric effects.
- Ekeberg, Dag,Morgenlie, Svein,Stenstrom, Yngve
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p. 779 - 786
(2007/10/03)
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- Methods for treating plants and enhancing plant growth using polyacylglycosides and/or polyalkylglycosides and formulations for same
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Methods and formulations for treating plants and enhancing plant growth and for safening high concentrations of one or more phytocatalysts, wherein one or more formulations, comprising, a high concentration of one or more phytocatalysts, and an effective amount of one or more polyacylglycosides and polyalkylglycosides; and isomers, and metabolites, salts, hydrates, esters, amines, and derivatives of the polyacylglycosides and polyalkylglycosides, and combinations thereof, is applied to the plants.
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- Conversion of D-ribo-3-hexosulose into D-ribulose and D-erythronic acid in aqueous medium
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The decomposition of D-ribo-3-hexosulose in water, studied by HPLC, gave D-ribulose (60-65percent) and D-erythronic acid (20percent), both isolated by column chromatography.D-Ribulose was characterized using LC-MS and NMR.From the latter technique, the ratio of three isomeric structures was determined.D-Erythronic acid was characterized by NMR.
- Wit, D. de,Rantwijk, F. van,Maat, L.,Kieboom, A. P. G.
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p. 271 - 274
(2007/10/02)
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- Synthesis of D-erythro-2-pentulose and D-threo-2-pentulose and analysis of the 13C- and 1H-n.m.r. spectra of the 1-13C- and 2-13C-substituted sugars.
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The pentuloses D-erythro-2-pentulose (1) and D-threo-2-pentulose (2) and their 1-13C- and 2-13C-substituted derivatives were prepared by hydrogenating the corresponding isotopically normal and 13C-substituted D-pentos-2-uloses with a Pd-carbon catalyst. The threo isomer and its labeled derivatives were alternatively prepared from isotopically normal and 13C-substituted D-xyloses with immobilized D-xylose (D-glucose) isomerase (E.C.5.3.1.5). The equilibrium compositions of 1 and 2 (furanose anomers and acyclic keto forms) in 2H2O were determined from 13C-n.m.r. spectra (75 MHz) of the 2-13C-labeled derivatives. The conformational properties of the cyclic and acyclic forms in 2H2O were assessed with the use of 1H-1H, 13C-1H, and 13C-13C spin-coupling constants obtained from 1H-n.m.r. (620 MHz) and 13C-n.m.r. (75 MHz) spectra. Compared with the structurally related aldotetrofuranoses the 2-pentulofuranoses more strongly prefer conformations in which the anomeric hydroxyl group is oriented quasi-axially. The strongly dipolarized carbonyl group in the acyclic keto forms of 1 and 2 appears to stabilize chain conformations having O-1 and O-3 eclipsed with the carbonyl oxygen.
- Vuorinen,Serianni
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- Reversible and in Situ Formation of Organic Arsenates and Vanadates as Organic Phosphate Mimics in Enzymatic Reactions: Mechanistic Investigation of Aldol Reactions and Synthetic Applications
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A synthetic strategy is developed that uses organic phosphate utilizing enzymes as catalysts and a mixture of an organic alcohol and inorganic arsenate or vanadate to replace the organic phosphate substrate.In this process, inorganic arsenate or vanadate reacts with the alcohol reversibly in situ to form a mixture of esters, one of which is accepted by the enzyme as a substrate.Examples of the utility of this approach are demonstrated in enzymatic aldol condensations catalyzed by fructose-1,6-diphosphate aldolase, fuculose-1-phosphate aldolase, and rhamnulose-1-phosphate aldolase with a mixture of dihydroxyacetone and inorganic arsenate as substrate.Several uncommon sugars and deoxy sugars are prepared on 5-17-mmol scales.Mechanistic studies on an aldol reaction indicate that the redox reaction between dihydroxyacetone and inorganic vanadate prohibits the use of such a mixture to replace dihydroxyacetone phosphate in enzymatic aldol condensations.
- Drueckhammer, Dale G.,Durrwachter, J. Robert,Pederson, Richard L.,Crans, Debbie C.,Daniels, Lacy,Wong, Chi-Huey
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- Aldol Reaction between Small Sugars. Preparation of DL-threo-2-Pentulose and DL-lyxo-3-Hexulose and their Isolation as O-Isopropylidene Derivatives
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The improved diastereoselectivity obtained with strongly basic anion-exchange resin as catalyst in aldol condensation between two-, three- and four-carbon "sugars" has been utilised in the preparation of DL-threo-2-pentulose and DL-lyxo-3-hexulose, which were isolated as their O-isopropylidene derivatives.A possible reason for the observe preference of formation of the lyxo-diastereomer in condensation between glycolaldehyde and glycero-tetrulose is suggested.
- Morgenlie, Svein
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p. 745 - 748
(2007/10/02)
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- Kinetics, Catalysis, and Mechanism of the Secondary Reaction in the Final Phase of the Formose Reaction
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In the final phase of the formose reaction sugars are formed by the reaction of glycolaldehyde, glyceraldehyde and dihydroxyacetone.The application of high-pressure liquid chromatography allows for the first time to investigate intermediate and final products quantitatively.The results of kinetical investigations allow to suggest a reaction mechanism for the secondary reaction in the final phase of the formose reaction.This mechanism is compared with that of the starting phase and other known mechanisms.From the results metal ion-catalyzed aldol reactions have to be assumed.
- Harsch, Guenther,Bauer, Hermann,Voelter, Wolfgang
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p. 623 - 635
(2007/10/02)
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- The Photochemistry of Ketones derived from Carbohydrates. Part 8. Type I Cleavage of 1,2:4,5-Di-O-isopropylidene-β-D-erythro-2,3-hexodiulose-2,6-pyranose: a Synthesis of D-Ribulose from D-Fructose
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Solutions of di-O-isopropylidene-β-D-erythro-2,3-hexodiulose-2,6-pyranose (8) in various solvents decarbonylate upon irradiation with u.v. light to give an anomeric mixture of 1,2:3,4-di-O-isopropylidene-D-ribulose (10) and (11), accompanied by variable amounts of the unstable olefin (12) and the aldehyde (13).Compound (13) was found to be a thermal breakdown product from the olefin (12).The photoproduct yields were sensitive to the solvent polarity.The furanose derivatives (10) and (11) were produced with a 1.2:1.0 ratio in 30, 35, and 45percent yields in methyl cyanide, benzene, and n-hexane, respectively.The D-ribulose derivatives (10) and (11) were produced on a preparative scale, isolated free from (12) and (13) by distillation, and hydrolysed to D-ribulose.
- Collins, Peter M.,Gupta, Paul,Travis, Anthony S.
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p. 277 - 281
(2007/10/02)
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