- Hydroxyapatite-Supported Polyoxometalates for the Highly Selective Aerobic Oxidation of 5-Hydroxymethylfurfural or Glucose to 2,5-Diformylfuran under Atmospheric Pressure
-
(NH4)5H6PV8Mo4O40 supported on hydroxyapatite (HAP) (PMo4V8/HAP (n)) was prepared through the ion exchange of hydroxy groups. This ion exchange favored the oxidative conversion of 5-hydroxymethylfurfural (5-HMF) to 2,5-diformylfuran (DFF) in a one-pot cascade reaction with 96.0 % conversion and 83.8 % yield under 10 mL/min of O2 flow. PMo4V8/HAP (31) was used to explore the production of DFF directly from glucose with the highest yield of 47.9 % so far under atmospheric oxygen, whereas the yield of DFF increased to 54.7 % in a one-pot and two-step reaction. These results indicated that the active sites in PMo4V8/HAP (31) retained their activities without any interference toward one another, which enabled the production of DFF in a more cost-saving way by only using oxygen and one catalyst in a one-step reaction. Meanwhile, the rigid structure of HAP and strong interaction in PMo4V8/HAP (31) allowed this catalyst to be reused for at least six times with high stability and duration.
- Guan, Hongyu,Li, Ying,Wang, Qiwen,Wang, Xiaohong,Yu, Hang
-
p. 997 - 1005
(2021/08/06)
-
- Few-Unit-Cell MFI Zeolite Synthesized using a Simple Di-quaternary Ammonium Structure-Directing Agent
-
Synthesis of a pentasil-type zeolite with ultra-small few-unit-cell crystalline domains, which we call FDP (few-unit-cell crystalline domain pentasil), is reported. FDP is made using bis-1,5(tributyl ammonium) pentamethylene cations as structure directing agent (SDA). This di-quaternary ammonium SDA combines butyl ammonium, in place of the one commonly used for MFI synthesis, propyl ammonium, and a five-carbon nitrogen-connecting chain, in place of the six-carbon connecting chain SDAs that are known to fit well within the MFI pores. X-ray diffraction analysis and electron microscopy imaging of FDP indicate ca. 10 nm crystalline domains organized in hierarchical micro-/meso-porous aggregates exhibiting mesoscopic order with an aggregate particle size up to ca. 5 μm. Al and Sn can be incorporated into the FDP zeolite framework to produce active and selective methanol-to-hydrocarbon and glucose isomerization catalysts, respectively.
- Abeykoon, Milinda,Al-Thabaiti, Shaeel,Bell, Alexis T.,Boscoboinik, J. Anibal,Dai, Heng,Dauenhauer, Paul,Dorneles de Mello, Matheus,Duan, Xuekui,Ghosh, Supriya,Kamaluddin, Huda Sharbini,Khan, Zaheer,Kumar, Gaurav,Li, Xinyu,Lu, Peng,Luo, Tianyi,Mkhoyan, K. Andre,Narasimharao, Katabathini,Qi, Liang,Rimer, Jeffrey D.,Tsapatsis, Michael
-
supporting information
p. 19214 - 19221
(2021/08/09)
-
- Method for preparing fructose (by machine translation)
-
The method comprises the following steps: (1) reacting glucose with a catalyst in the presence of alcohol and carrying out reaction to obtain fructose-containing product; wherein the weight ratio of the glucose to the mixture of the titanium silicalite molecular sieve and the tin-silicon molecular sieve 50 - 600 is below 30 °C: (100 °C 0.1 - 6 1 1 - 10h) The method disclosed by the invention has high glucose conversion rate and fructose yield. (by machine translation)
- -
-
Paragraph 0070-0101
(2020/07/02)
-
- Method for preparing lactic acid through catalytically converting carbohydrate
-
The invention relates to a method for preparing lactic acid through catalytically converting carbohydrate, and in particular, relates to a process for preparing lactic acid by catalytically convertingcarbohydrate under hydrothermal conditions. The method disclosed by the invention is characterized by specifically comprising the following steps: 1) adding carbohydrate and a catalyst into a closedhigh-pressure reaction kettle, and then adding pure water for mixing; 2) introducing nitrogen into the high-pressure reaction kettle to discharge air, introducing nitrogen of 2 MPa, stirring and heating to 160-300 DEG C, and carrying out reaction for 10-120 minutes; 3) putting the high-pressure reaction kettle in an ice-water bath, and cooling to room temperature; and 4) filtering the solution through a microporous filtering membrane to obtain the target product. The method can realize high conversion rate of carbohydrate and high yield of lactic acid, and has the advantages of less catalyst consumption, good circularity, small corrosion to reaction equipment and the like.
- -
-
Paragraph 0029-0040
(2020/11/01)
-
- Bi-Functional Magnesium Silicate Catalyzed Glucose and Furfural Transformations to Renewable Chemicals
-
Bio-refinery is attracting significant interest to produce a wide range of renewable chemicals and fuels from biomass that are alternative to fossil fuel derived petrochemicals. Similar to petrochemical industries, bio-refinery also depends on solid zeolite catalysts. Acid-base catalysis plays pivotal role in producing a wide range of chemicals from biomass. Herein, the Mg framework substituted MTW zeolite is synthesized and explored in the valorisation of glucose and furfural. Bi-functional (acidic and basic) characteristics are confirmed using pyridine adsorbed FT?IR analysis and NH3 and CO2 temperature-programmed desorption techniques. Textural properties and morphological information are retrieved from N2-sorption, X-ray photoelectron spectroscopy, and electron microscopy. The activity of the catalyst is demonstrated in the selective isomerisation of glucose to fructose in ethanol. Glucose is converted to methyl lactate in high yield using the same catalyst. Further, the bi-functional activity of this catalyst is demonstrated in the production of fuel precursor by the reaction of furfural and isopropanol. Mg?MTW zeolite exhibits excellent activity in the production of all these chemicals and fuel derivative. The catalyst exhibits no significant loss in the activity even after five recycles. One simple catalyst affording three renewable synthetic intermediates from glucose and furfural will attract significant attention to catalysis researchers and industrialists.
- Kumar, Abhinav,Srivastava, Rajendra
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p. 4807 - 4816
(2020/08/24)
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- PROCESSES FOR PREPARING SORBOSE FROM GLUCOSE
-
Processes for converting glucose to sorbose with tailored selectivity. The processes include contacting glucose with a silica-containing structure that includes a zeolite having a topology of a 10-membered ring or smaller and Lewis acidic M4+ framework centers, wherein M is Ti, Sn, Zr, or Hf. Contacting the glucose is conducted under reaction conditions sufficient to isomerize the glucose to sorbose.
- -
-
Paragraph 0012-0013; 0016-0018; 0035-0037; 0038
(2020/08/25)
-
- Characterization of alditol oxidase from Streptomyces coelicolor and its application in the production of rare sugars
-
A synthetic platform for the cascade synthesis of rare sugars using Escherichia coli whole cells was established. In the cascade, the donor substrate dihydroxyacetone phosphate (DHAP) was generated from glycerol by glycerol kinase (GK) and glycerol phosphate oxidase (GPO). The acceptor D-glyceraldehyde was directly produced from glycerol by an alditol oxidase. Then, the aldol reaction between DHAP and D-glyceraldehyde was performed by L-rhamnulose-1-phosphate aldolase (RhaD) to generate the corresponding sugar-1-phosphate. Finally, the phosphate group was removed by fructose-1-phosphatase (YqaB) to obtain the rare sugars D-sorbose and D-psicose. To accomplish this goal, the alditol oxidase from Streptomyces coelicolor (AldOS.coe) was expressed in E. coli and the purified AldOS.coe was characterized. Furthermore, a recombinant E. coli strain overexpressing six enzymes including AldOS.coe was constructed. Under the optimized conditions, it produced 7.9 g/L of D-sorbose and D-psicose with a total conversion rate of 17.7% from glycerol. This study provides a useful and cost-effective method for the synthesis of rare sugars.
- Chen, Zhou,Gao, Xiao-Dong,Li, Fen,Li, Zijie,Wang, Ning
-
-
- ENZYMATIC PRODUCTION OF D-ALLULOSE
-
The current disclosure provides a process for enzymatically converting a saccharide into allulose. The invention also relates to a process for preparing allulose where the process involves converting fructose 6-phosphate (F6P) to allulose 6-phosphate (A6P), catalyzed by allulose 6-phosphate 3-epimerase (A6PE), and converting the A6P to allulose, catalyzed by allulose 6-phosphate phosphatase (A6PP).
- -
-
-
- Characterization of a novel D-arabinose isomerase from Thermanaeromonas toyohensis and its application for the production of D-ribulose and L-fuculose
-
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
-
-
- SYNTHESIS OF D-ALLULOSE
-
The invention relates to a process for the synthesis of a product saccharide, preferably of D-allulose from an educt saccharide, preferably from D-fructose under heterogeneous or homogeneous catalysis which includes chemical and/or enzymatic catalysis. The synthesis is performed in at least two reactors that are arranged in series and the reaction product exiting the first reactor is subjected to chromatographic separation before it enters the second reactor. Preferably, the chromatographic separation is integrated in a simulated moving bed.
- -
-
Paragraph 0309-0316
(2019/10/30)
-
- Role of the Strong Lewis Base Sites on Glucose Hydrogenolysis
-
This work reports the individual role of strong Lewis base sites on catalytic conversion of glucose hydrogenolysis to acetol/lactic acid, including glucose isomerisation to fructose and pyruvaldehyde rearrangement/hydrogenation to acetol/lactic acid. Las
- Yazdani, Parviz,Wang, Bo,Gao, Feng,Kawi, Sibudjing,Borgna, Armando
-
p. 3845 - 3853
(2018/07/31)
-
- METHOD OF PRODUCING HIGH PURITY D-PSICOSE
-
Disclosed herein is a method of producing D-psicose. The method of producing D-psicose includes subjecting D-fructose to D-psicose epimerization to produce a D-psicose-containing solution, subjecting the D-psicose-containing solution to first cooling and ion purification, subjecting the purified D-psicose-containing solution to first concentration and second cooling, subjecting the D-psicose-containing solution, which has been subjected to first concentration and second cooling, to chromatography to obtain a D-fructose-containing mother liquor and a D-psicose-containing separated solution, and subjecting the D-psicose-containing separated solution to second concentration and third cooling to obtain D-psicose crystals, wherein the D-fructose-containing mother liquor produced by chromatography is reused in the D-psicose epimerization.
- -
-
Page/Page column 9; 10
(2017/09/15)
-
- PRODUCTION OF ALPHA-HYDROXY CARBOXYLIC AIDS AND ESTERS FROM HIGHER SUGARS USING TANDEM CATALYST SYSTEMS
-
The present disclosure is directed to methods and composition used in the preparation of alpha-hydroxy carboxylic acids and esters from higher sugars using a tandem catalyst system comprising retro-aldol catalysts and Lewis acid catalysts. In some embodiments, these alpha-hydroxy carboxylic acids may be prepared from pentoses and hexoses. The retro-aldol and Lewis catalysts may be characterized by their respective ability to catalyze a 1,2-carbon shift reaction and a 1,2-hydride shift reaction on an aldose or ketose substrate.
- -
-
Page/Page column 2; 13-14
(2017/02/09)
-
- A catalyzed by a chemical method, a method of glucose isomerization to fructose
-
The invention discloses a chemical method for catalyzing glucose into fructose through isomerization, and relates to fructose. The method comprises the following steps: mixing a water solution containing Mg(NO3)2.6H2O, Al(NO3)3.6H2O, and Zr(NO3)4.5H2O/Sn(NO3).6H2O/Cu(NO3)2.3H2O with a NaOH water solution and a Na2CO3 water solution, wherein the metal molar mass ratio of Mg:Al:M is equal to 3:1:1, M represents Zr, Sn, or Cu, pH is 8 to 8, and the temperature is 60 DEG C; carrying out aging on the precipitate in the mother liquid, then carrying out static crystallization, drying so as to obtain the trinary metal hydrotalcite, adding the trinary metal hydrotalcite into a glucose solution to carry out reactions, filtering so as to obtain isomerized glucose solution and a solid hydrotalcite catalyst, recycling the catalyst, and finally subjecting the filtrate to vacuum rotation evaporation so as to obtain a condensed fructose liquid, wherein the weight ratio of the trinary metal hydrotalcite to the glucose to solvent (water) is (1-4):(1-10):40.
- -
-
Paragraph 0043; 0044
(2017/02/28)
-
- METHOD FOR PRODUCING CARBOHYDRATES FROM DIHYDROXYACETONE
-
The present invention relates to the use of dihydroxyacetone ("DHA") in the preparation of a number of natural and rare carbohydrates. The present invention comprises three stages. In the first stage of the present invention, syngas and formaldehyde are produced from natural gas, biogas, biomass and C02 from industrial plants including electricity generating plants, steel mills, cement factories and bio refineries. In the second stage of the present invention, formaldehyde and syngas from first stage are condensed to produce DHA. In the third stage of the present invention, DHA serves as a starting material for the synthesis of natural and rare carbohydrates using enzymes belonging to isomerase, aldolases, epimerase and transketolase groups.
- -
-
Paragraph 00159
(2016/12/26)
-
- Characterization of glycerol phosphate oxidase from Streptococcus pneumoniae and its application for ketose synthesis
-
Glycerol phosphate oxidase from Streptococcus pneumoniae (GPOS.pne) was purified and characterized. By the actions of GPOS.pne and dihydroxyacetone phosphate (DHAP)-dependent aldolases, various ketoses including rare sugars were synthesized with glyceraldehydes as acceptors in a one-pot four-enzyme system.
- Li, Zijie,Qiao, Yingxin,Cai, Li,Nakanishi, Hideki,Gao, Xiao-Dong
-
supporting information
p. 504 - 507
(2015/03/05)
-
- Directed divergent evolution of a thermostable D-tagatose epimerase towards improved activity for two hexose substrates
-
Functional promiscuity of enzymes can often be harnessed as the starting point for the directed evolution of novel biocatalysts. Here we describe the divergent morphing of an engineered thermostable variant (Var8) of a promiscuous D-tagatose epimerase (DTE) into two efficient catalysts for the C3 epimerization of d-fructose to d-psicose and of L-sorbose to L-tagatose. Iterative single-site randomization and screening of 48 residues in the first and second shells around the substratebinding site of Var8 yielded the eight-site mutant IDF8 (nine-fold improved kcat for the epimerization of D-fructose) and the six-site mutant ILS6 (14-fold improved epimerization of L-sorbose), compared to Var8. Structure analysis of IDF8 revealed a charged patch at the entrance of its active site; this presumably facilitates entry of the polar substrate. The improvement in catalytic activity of variant ILS6 is thought to relate to subtle changes in the hydration of the bound substrate. The structures can now be used to select additional sites for further directed evolution of the ketohexose epimerase.
- Bosshart, Andreas,Hee, Chee Seng,Bechtold, Matthias,Schirmer, Tilman,Panke, Sven
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p. 592 - 601
(2015/04/13)
-
- Facile enzymatic synthesis of ketoses
-
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
-
p. 12654 - 12658
(2015/10/28)
-
- Catalytic effect of aluminium chloride on the example of the conversion of sugar model compounds
-
Abstract In this work, the catalytic effect of the Bronsted acid hydrochloric acid, the Bronsted base sodium hydroxide and the Lewis acid AlCl3 on the conversion of biomass derived carbohydrates is investigated. On the example of the glycolaldehyde conversion, it is shown that the Lewis acid catalyses the ketol-endiol-tautomerism, the dehydration, the retro-aldol-reaction and the benzilic-acid-rearrangement. The main products are C4- and C6-carbohydrates as well as their secondary products 2-hydroxybut-3-enoic acid 1 and several furans. Under the same reaction conditions hydrochloric acid catalyzes mainly the dehydration and sodium hydroxide the tautomerism and subsequent aldolization.
- Schwiderski, Martin,Kruse, Andrea
-
-
- Transforming flask reaction into cell-based synthesis: Production of polyhydroxylated molecules via engineered Escherichia coli
-
Dihydroxyacetone phosphate (DHAP)-dependent aldolases have been intensively studied and widely used in the synthesis of carbohydrates and complex polyhydroxylated molecules. However, strict specificity toward donor substrate DHAP greatly hampers their synthetic utility. Here, we transformed DHAP-dependent aldolases-mediated by in vitro reactions into bioengineered Escherichia coli (E. coli). Such flask-to-cell transformation addressed several key issues plaguing in vitro enzymatic synthesis: (1) it solves the problem of DHAP availability by in vivo-hijacking DHAP from the glycolysis pathway of the bacterial system, (2) it circumvents purification of recombinant aldolases and phosphatase, and (3) it dephosphorylates the resultant aldol adducts in vivo, thus eliminating the additional step for phosphate removal and achieving in vivo phosphate recycling. The engineered E. coli strains tolerate a wide variety of aldehydes as acceptor and provide a set of biologically relevant polyhydroxylated molecules in gram scale.
- Wei, Mohui,Li, Zijie,Li, Tiehai,Wu, Baolin,Liu, Yunpeng,Qu, Jingyao,Li, Xu,Li, Lei,Cai, Li,Wang, Peng George
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p. 4060 - 4065
(2015/11/11)
-
- Synthesis of D-sorbose and D-psicose by recombinant Escherichia coli
-
In the current work, the in vitro synthetic system for rare sugars was successfully transformed into an engineered Escherichia coli with a plasmid containing both the aldolase RhaD and phosphatase YqaB. By taking advantage of the inherent biosynthetic pathways in E. coli, this approach permits the use of simple and cheap glycerol for the synthesis of DHAP in vivo. Moreover, the introduction of the phosphatase into the E. coli system allows for the removal of the phosphate group on the synthetic intermediate to yield the neutral rare sugars, which can be readily secreted to the medium without accumulation in the cell.
- Li, Zijie,He, Beibei,Gao, Yahui,Cai, Li
-
p. 349 - 357
(2015/10/19)
-
- Titanium-beta zeolites catalyze the stereospecific isomerization of d -glucose to l -sorbose via intramolecular C5-C1 hydride shift
-
Pure-silica zeolite beta containing Lewis acidic framework Ti4+ centers (Ti-Beta) is shown to catalyze the isomerization of d-glucose to l-sorbose via an intramolecular C5-C1 hydride shift. Glucose-sorbose isomerization occurs in parallel to glucose-fructose isomerization on Ti-Beta in both water and methanol solvents, with fructose formed as the predominant product in water and sorbose as the predominant product in methanol (at 373 K) at initial times and over the course of >10 turnovers. Isotopic tracer studies demonstrate that 13C and D labels placed respectively at the C1 and C2 positions of glucose are retained respectively at the C6 and C5 positions of sorbose, consistent with its formation via an intramolecular C5-C1 hydride shift isomerization mechanism. This direct Lewis acid-mediated pathway for glucose-sorbose isomerization appears to be unprecedented among heterogeneous or biological catalysts and sharply contrasts indirect base-mediated glucose-sorbose isomerization via 3,4-enediol intermediates or via retro-aldol fragmentation and recombination of sugar fragments. Measured first-order glucose-sorbose isomerization rate constants (per total Ti; 373 K) for Ti-Beta in methanol are similar for glucose and glucose deuterated at the C2 position (within a factor of ~1.1), but are a factor of ~2.3 lower for glucose deuterated at each carbon position, leading to H/D kinetic isotope effects expected for kinetically relevant intramolecular C5-C1 hydride shift steps. Optical rotation measurements show that isomerization of d-(+)-glucose (92% enantiomeric purity) with Ti-Beta in water (373 K) led to the formation of l-(-)-sorbose (73% enantiomeric purity) and d-(-)-fructose (87% enantiomeric purity) as the predominant stereoisomers, indicating that stereochemistry is preserved at carbon centers not directly involved in intramolecular C5-C1 or C2-C1 hydride shift steps, respectively. This new Lewis acid-mediated rearrangement of glucose to sorbose does not appear to have a metalloenzyme analog.
- Gounder, Rajamani,Davis, Mark E.
-
p. 1469 - 1476
(2013/07/26)
-
- Productive sugar isomerization with highly active Sn in dealuminated β zeolites
-
A water-tolerant Lewis acid catalyst was synthesized by grafting Sn IV in isopropanol under reflux onto dealuminated zeolites with the BEA (β) topology. This synthesis method allows the production of highly active Snβ-type catalysts without the need for long hydrothermal syntheses or hydrogen fluoride, while using cheap Sn-precursors, industrially available β zeolites and standard catalyst synthesis unit operations. Extensive characterization of the best catalyst shows highly dispersed Sn in the zeolite matrix (XRD, 29Si MAS NMR and 1H MAS NMR) without the formation of SnO2 (XRD and UV-Vis). The catalyst was tested for the model isomerization of sugars such as glucose to fructose. The catalytic activity proved to be purely heterogeneous and the catalyst was recycled and reused without significant loss in activity. Isomerization productivities above 4 kg product per kg of catalyst per hour are reported with appreciably low Sn loadings, corresponding to exceptionally high turnover frequencies, viz. 500 cycles per Sn per hour at 110 °C, which surpass the activity per Sn of the original hydrothermally synthesized Snβ.
- Dijkmans, Jan,Gabriels, Dries,Dusselier, Michiel,De Clippel, Filip,Vanelderen, Pieter,Houthoofd, Kristof,Malfliet, Annelies,Pontikes, Yiannis,Sels, Bert F.
-
p. 2777 - 2785
(2013/10/08)
-
- Molecular characterization of a thermostable l-fucose isomerase from Dictyoglomus turgidum that isomerizes l-fucose and d-arabinose
-
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
-
experimental part
p. 1926 - 1934
(2012/09/22)
-
- Synthesis of rare sugars with l-fuculose-1-phosphate aldolase (FucA) from Thermus thermophilus HB8
-
We report herein a one-pot four-enzyme approach for the synthesis of the rare sugars d-psicose, d-sorbose, l-tagatose, and l-fructose with aldolase FucA from a thermophilic source (Thermus thermophilus HB8). Importantly, the cheap starting material DL-GP (DL-glycerol 3-phosphate), was used to significantly reduce the synthetic cost.
- Li, Zijie,Cai, Li,Qi, Qingsheng,Styslinger, Thomas J.,Zhao, Guohui,Wang, Peng George
-
supporting information; experimental part
p. 5084 - 5087
(2011/10/09)
-
- Cloning, expression, and characterization of a d-psicose 3-epimerase from clostridium cellulolyticum H10
-
The noncharacterized protein ACL75304 encoded by the gene Ccel-0941 from Clostridium cellulolyticum H10 (ATCC 35319), previously proposed as the xylose isomerase domain protein TIM barrel, was cloned and expressed in Escherichia coli. The expressed enzyme was purified by nickel-affinity chromatography with electrophoretic homogeneity and then characterized as d-psicose 3-epimerase. The enzyme was strictly metal-dependent and showed a maximal activity in the presence of Co2+. The optimum pH and temperature for enzyme activity were 55 °C and pH 8.0. The half-lives for the enzyme at 60 °C were 6.8 h and 10 min when incubated with and without Co2+, respectively, suggesting that this enzyme was extremely thermostable in the presence of Co2+ but readily inactivated without metal ion. The Michaelis-Menten constant (Km), turnover number (kcat), and catalytic efficiency (kcat/Km) values of the enzyme for substrate d-psicose were estimated to be 17.4 mM, 3243.4 min-1, and 186.4 mM min-1, respectively. The enzyme carried out the epimerization of d-fructose to d-psicose with a conversion yield of 32% under optimal conditions, suggesting that the enzyme is a potential d-psicose producer.
- Mu, Wanmeng,Chu, Feifei,Xing, Qingchao,Yu, Shuhuai,Zhou, Leon,Jiang, Bo
-
scheme or table
p. 7785 - 7792
(2012/07/13)
-
- Mixed-acid systems for the catalytic synthesis of methyl levulinate from cellulose
-
Mixed-acid systems consisting of both Lewis and Bronsted acids were found to be efficient catalysts for direct synthesis of methyl levulinate from cellulose. The Royal Society of Chemistry.
- Tominaga, Ken-Ichi,Mori, Atsushi,Fukushima, Yuriko,Shimada, Shigeru,Sato, Kazuhiko
-
experimental part
p. 810 - 812
(2011/06/22)
-
- Enzymatic synthesis of d-sorbose and d-psicose with aldolase RhaD: Effect of acceptor configuration on enzyme stereoselectivity
-
It was previously reported that DHAP-dependent aldolase RhaD selectively chooses l-glyceraldehyde from racemic glyceraldehyde to produce l-fructose exclusively. Contrastingly, we discovered that d-glyceraldehyde is also tolerated as an acceptor and the stereoselectivity of the enzyme is lost in the corresponding aldol addition. Furthermore, we applied this property to efficiently synthesize two rare sugars d-sorbose and d-psicose.
- Li, Zijie,Cai, Li,Qi, Qingsheng,Wang, Peng George
-
supporting information; experimental part
p. 7081 - 7084
(2012/01/13)
-
- Crystal structure, solubility, and mutarotation of the rare monosaccharide D-psicose
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X-ray crystal analysis for D-psicose (C3-position epimer of D-fructose) crystallized from aqueous solution was successfully performed for the first time. It was confirmed that D-psicose crystallized solely as β-D-pyranose with 1C (1C4 (d)) conformation. The crystal system (orthorhombic), space group (#19, P212121), and number of molecules per unit cell (Z = 4) are the same as those for β-D-fructopyranose, α-L-sorbopyranose, and α-D-tagatopyranose. Solubility of D-psicose at 25 °C was 291 g per 100 g water. Mutarotation was further investigated recording the time course of specific rotation [α] at 589 nm after the dissolution of D-psicose in water. It is thought that [α] for β-D-psicopyranose in water may be ca.-85degdm -1g-1 cm3. The time course of absorbance at 280 nm after the dissolution of D-psicose was also measured to see the development of open-chain carbonyl-form in the solution, and the first-order kinetic behavior with the rate constant k = 4.44 ms-1 was confirmed. Assuming the equilibrium content of carbonyl-form of D-psicose as 0.2%, the molar absorption coefficient, ε, for the carbonyl-form was estimated to be 160cm-1 M-1.
- Fukada, Kazuhiro,Ishii, Tomohiko,Tanaka, Katsushi,Yamaji, Masatsugu,Yamaoka, Yuya,Kobashi, Ken-Ichi,Izumori, Ken
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scheme or table
p. 1193 - 1197
(2010/12/25)
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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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- Osmium catalyzed dihydroxylation of 1,2-dioxines: A new entry for stereoselective sugar synthesis
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A series of 3,6-substituted 3,6-dihydro-1,2-dioxines were dihydroxylated with osmium tetroxide to furnish 1,2-dioxane-4,5-diols (peroxy diols) in yields ranging from 33% to 98% and with de values not less than 90%. The peroxy diols were then reduced to generate a stereospecific tetraol core with R,R,S,S or "allitol" stereochemistry. The peroxy diols and their acetonide derivatives were also ring-opened with Co(II) salen complexes to give novel hydroxy ketones in 77-100% yield, including the natural sugar psicose. Importantly, preliminary work on the catalytic asymmetric ring-opening of meso-peroxy diols using the Co(II) Jacobsens's catalyst indicates that asymmetric sugar synthesis from 1,2-dioxines is possible.
- Robinson, Tony V.,Taylor, Dennis K.,Tiekink, Edward R. T.
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p. 7236 - 7244
(2007/10/03)
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- Fully active alternansucrases partially deleted in its carboxy-terminal and amino-terminal domains and mutants thereof
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Nucleic acid sequences of truncated or mutated alternansucrases, vectors containing these nucleic acids sequences, host cells transformed with the nucleic acid sequences encoding truncated or mutated alternansucrases are provided. Furthermore, a process to recombinantly alternansucrase with a high level of expression, while retaining the enzymatic activity is described.
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Page/Page column 15-16
(2008/06/13)
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- Borate as a phosphate ester mimic in aldolase-catalyzed reactions: Practical synthesis of L-fructose and L-iminocyclitols
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Dihydroxyacetone phosphate (DHAP)-dependent aldolases have been widely used for the organic synthesis of unnatural sugars or derivatives. The practicality of using DHAP-dependent aldolases is limited by their strict substrate specificity and the high cost and instability of DHAP. Here we report that the DHAP-dependent aldolase L-rhamnulose 1-phosphate aldolase (RhaD) accepts dihydroxyacetone (DHA) as a donor substrate in the presence of borate buffer, presumably by reversible in situ formation of DHA borate ester. The reaction appears to be irreversible, with the products thermodynamically trapped as borate complexes. We have applied this discovery to develop a practical one-step synthesis of the non-caloric sweetener L-fructose. L-Fructose was synthesized from racemic glyceraldehyde and DHA in the presence of RhaD and borate in 92% yield on a gram scale. We also synthesized a series of L-iminocyclitols, which are potential glycosidase inhibitors, in only two steps.
- Sugiyama, Masakazu,Hong, Zhangyong,Whalen, Lisa J.,Greenberg, William A.,Wong, Chi-Huey
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p. 2555 - 2559
(2007/10/03)
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- Direct organocatalytic de novo synthesis of carbohydrates
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One small step for a catalyst: A biomimetic asymmetric synthesis of carbohydrates was accomplished by a proline-catalyzed aldol reaction of 2,2-dimethyl-1,3-dioxan-5-one as the methylene component with various aldehydes. This new organocatalytic C3+Cn strategy leads directly to selectively protected simple sugars and amino sugars.
- Enders, Dieter,Grondal, Christoph
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p. 1210 - 1212
(2007/10/03)
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- Catalytic asymmetric epoxidation
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The present invention provides a variety of methods that are based on stereoselective epoxidation of an olefin by an epoxidizing agent derived from a reaction between an oxidizing agent and a chiral ketone. For example, present invention provides methods for producing an epoxide from an olefin, for increasing a relative concentration of at least one stereoisomer of an olefin, and for stereoselectively producing an α-acyloxy carbonyl compound. Preferably, the chiral ketone is of the formula: or a derivative thereof which is capable of converting to the chiral ketone of Formula I under the reaction conditions, where a, b, n, X, R1, R2, R3, R4, R5and R6are those defined herein.
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- Formation of 3-hexuloses in aldol reactions, analysis of the products as their O-isopropylidene derivatives by GC-MS
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A method for analysis of mixtures of 3-hexuloses by gas chromatography mass spectrometry of their di-O-isopropylidene derivatives has been elaborated. The origin of characteristic fragment ions in the mass spectra is suggested on the basis of the spectra of d12 analogues, obtained by acetonation with acetone-d6 and on MS/MS investigations. The method has been applied to product mixtures from aldol reactions between glycero-tetrulose and glycolaldehyde and between 2-pentuloses and formaldehyde. An interesting result is the formation of ribo-3-hexulose with a high degree of stereoselectivity in alkali catalysed reaction between erythro-2-pentulose and formaldehyde.
- Ekeberg, Dag,Morgenlie, Svein
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p. 2171 - 2176
(2007/10/03)
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- One-pot synthesis of L-fructose using coupled multienzyme systems based on rhamnulose-1-phosphate aldolase
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Two methods have been developed for the highly efficient enzymatic synthesis of L-fructose: one is based on rhamnulose-1-phosphate aldolase and acid phosphatase using racemic glyceraldehyde and dihydroxyacetone phosphate as substrates; the other is to gen
- Franke, Dirk,Machajewski, Timothy,Hsu, Che-Chang,Wong, Chi-Huey
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p. 6828 - 6831
(2007/10/03)
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- Catalytic asymmetric epoxidation
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The present invention provides a variety of methods that are based on stereoselective epoxidation of an olefin by an epoxidizing agent derived from a reaction between an oxidizing agent and a chiral ketone. For example, present invention provides methods for producing an epoxide from an olefin, for increasing a relative concentration of at least one stereoisomer of an olefin, and for stereoselectively producing an α-acyloxy carbonyl compound. Preferably, the chiral ketone is of the formula: or a derivative thereof which is capable of converting to the chiral ketone of Formula I under the reaction conditions, where a, b, n, X, R1, R2, R3, R4, R5 and R6 are those defined herein.
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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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- Degradation of sucrose, glucose and fructose in concentrated aqueous solutions under constant pH conditions at elevated temperature
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The degradation of sucrose can decrease sucrose yield, reduce the efficiency of sugar factory and refinery processes, and affect end product quality. Characterization of sucrose degradation under modeled industrial processing conditions will underpin further technological improvements. Effects of constant reaction pH on sucrose degradation were investigated using simulated industrial model systems (100 °C; 65 °Brix [% dissolved solids]; N2; 0.05-3 mol NaOH titrant; 8 h), with the use of an autotitrator. Reaction pH values ranged from 4.40 to 10.45. Polarimetry and ion chromatography with integrated pulsed amperometric detection (IC-IPAD) were used to quantify sucrose degradation and first-order reaction constants were calculated. Minimum sucrose degradation occurred between pH 6.45 - 8.50, with minimum color formation between pH's 4.40 - 7.00. Polarimetry, often used in U.S. sugar factories and refineries to monitor chemical sucrose losses, was shown not to be viable to measure sucrose degradation under alkaline conditions, because of the formation of fructose degradation products with an overall positive optical rotation. For comparison, fructose and glucose (80°C; 65 °Brix; N2; 3 mol NaOH; 2 h) were also degraded at constant pH 8.3 conditions. For sucrose, fructose, and glucose, formation of organic acids on.
- Eggleston,Vercellotti
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p. 1305 - 1318
(2007/10/03)
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- Stereospecific molybdic acid-catalyzed isomerization of 2-hexuloses to branched-chain aldoses
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On treatment with a catalytic amount of molybdic acid in aqueous solution, the 2-ketohexoses D-fructose, L-sorbose and D-tagatose undergo a stereospecific intramolecular rearrangement to give the corresponding 2-C-(hydroxymethyl)aldoses, 2-C-(hydroxymethyl)-D-ribose (D-hamamelose), 2-C-(hydroxymethyl)-L-lyxose, and 2-C-(hydroxymethyl)-D-xylose, respectively. At equilibrium, the ratio of 2-ketose to 2-C-(hydroxymethyl)aldose ranged from 14:1 (fructose) to 32:1 (sorbose). A similar treatment of D-psicose failed to yield a significant amount of the corresponding branched-chain aldose. The equilibria can be shifted with the addition of boric acid to the reaction mixture; under these conditions, ratios of 3:1 and 7:1 were obserwed for D-fructose and L-sorbose, respectively. A mechanistic study with D-(3-13C)fructose afforded D-(1-13C)hamamelose, thus confirming C-3 - C-4 bond cleavage with concomitant C-2 - C-3 transposition suggested from recent studies with D-(2-13C)fructose. Copyright (C) 1999 Elsevier Science Ltd.
- Hricoviniova-Bilikova, Zuzana,Hricovini, Milos,Petrusova, Maria,Serianni, Anthony S.,Petrus, Ladislav
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- Synthesis of carbohydrates via tandem use of the osmium-catalyzed asymmetric dihydroxylation and enzyme-catalyzed aldol addition reactions
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A new strategy is described for the asymmetric synthesis of carbohydrate derivatives via the tandem use of the osmium-catalyzed asymmetric dihydroxylation (AD) and aldolase-catalyzed aldol addition reactions. Both D- and L-forms of fructose, 6-deoxy-galacto-2-heptulose, and 6-phenyl-galacto-2-hexulose were synthesized to illustrate this methodology.
- Henderson, Ian,Sharpless, K. Barry,Wong, Chi-Huey
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p. 558 - 561
(2007/10/02)
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- Facile Synthesis of the Next Higher Ketoses from Aldoses
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A novel and facile synthesis of the next higher ketohexoses in high yield is successfully achieved by treating aldopentoses with formaldehyde in the presence of 3-ethylbenzothiazolium bromide as a catalyst.
- Matsumoto, Toshihiko,Enomoto, Tatsuya,Kurosaki, Toshikazu
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p. 610 - 611
(2007/10/02)
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- EVIDENCE OF STABLE HYDROGEN-BONDED IONS DURING ISOMERZATION OF HEXOSES IN ALKALI
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Epimeric pairs of aldohexoses and related ketohexose were isomerized in aqueous KOH at various temperatures and pH values, and the mixtures then analyzed by h.p.l.c. on either a cation-exchange resin or a reversed-phase column.It was found that the propertions of starting aldohexoses remaining after several days often exceeded those of the same that were formed from the epimeric aldoses and the corresponding ketoses.The difference with allose, gulose, and mannose was much larger than with other aldohexoses.These differences are rationalized by assuming that anomers having the OH groups attached to C-1, C-2, and C-3 in an axial-equatorial-axial or an equatorial-axial-equatorial arrangement form especially stable, hydrogen-bonded ions or molecular complexes that disturb the equilibrium state and affect the isomerization and mutarotation reactions.
- El Khadem, Hassan S.,Ennifar, Sofiane,Isbell, Horace S.
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- Changes in Stereoselectivity in the Triose Aldol Condensation with Incresed Concentration of Alkaline Earth Metal Ions
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The presence of strontium and calcium chlorides in the triose aldol condensation has been found to affect the diastereoselectivity markedly.Whereas arabino-2-hexulose (fructose) is the major product under ordinary conditions, high concentrations of the alkaline-earth metal ions cause a change in favour of the xylo- and lyxo-diastereomers.No such effect was observed when high concentrations of alkali-metal chlorides were used.
- Morgenlie, Svein
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p. 546 - 549
(2007/10/02)
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- Alkaline degradation of monosaccharides V: Kinetics of the alkaline isomerization and degradation of monosaccharides
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A new kinetic model for the alkaline isomerization and degradation of monosaccharides is presented which includes the interconversion of D-glucose, D-fructose, D-mannose and D-psicose.Computer simulations used in this model fit the experimental data and allow the determination of all relevant rate constants.Additionally, it has been established that, for the alkaline degradation of either D-fructose, D-glucose or D-mannose, substantial amounts of acidic products, i.e. ca. 65percent and ca. 20percent, are formed via D-fructose and D-psicose, respectively. - The influence of some reaction parameters on the pseudo-first-order rate constants involved in the kinetic model has been investigated.The enolization of monosaccharides appears to be the rate-limiting step in both the isomerization and the degradation reactions.The enolization rate is markedly enhanced at higher HO- concentration or by the addition of calcium(II).Direct retro-aldolization of D-fructose and D-psicose occurs at -> > 10-2 M or in the presence of calcium(II), leading to an additional increase in the degradation rate towards lactic acid.The shift of the isomerization equilibrium by borate towards D-fructose and D-psicose is accompanied by a decrease of the degradation rate constants, due to stabilization of the monosaccharides as their borate esters.
- Bruijn, J. M. de,Kieboom, A. P. G.,Bekkum, H. van
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- Synthesis of L-fructose and derivatives thereof
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It is disclosed that L-fructose can be produced in high yield from L-sorbose. The process involves the inversion of the hydroxyl groups on carbon atoms C3 and C4 of L-sorbose to produce L-fructose. This inversion can be accomplished in simple, commercial equipment with the aid of common reagents. L-sorbose or an appropriately blocked derivative thereof is reacted so as to introduce or create a good leaving group, preferably mesyl or tosyl, at chiral carbon C3 thereby displacing the hydroxyl previously at that position. The leaving group is then displaced, preferably under alkaline conditions, in such a way that the hydroxyl oxygen atom at chiral carbon C4 attaches to chiral carbon C3, thereby displacing the leaving group while forming a 3,4-oxirane (epoxide) ring. The 3,4-oxirane ring forms in a downward position relative to the Haworth presentation thereby inverting chiral carbon C3 during formation of the 3,4-oxirane ring. The 3,4-oxirane ring is then opened under acidic or alkaline conditions to yield a sugar ring with a hydroxyl group in a position above the sugar ring at chiral carbon C4, and a hydroxyl group in a downward position at C3. Removal of any remaining blocking groups yields L-fructose. This may be accomplished by acid hydrolysis. There are also disclosed novel classes of compounds which act as intermediaries in the synthesis of L-fructose.
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