Showing papers on "Aldose published in 2001"
TL;DR: The main reaction products in monosaccharide-casein systems, which were heated at 120 degrees C and pH 6.7, were identified and quantified, and the reaction pathways were established and put together into a model which will be evaluated by kinetic modeling in a subsequent paper.
Abstract: The Maillard reaction is important during the heating and processing of foods for its contribution to food quality. To control a reaction as complex as the Maillard reaction, it is necessary to study the reactions of interest quantitatively. In this paper the main reaction products in monosaccharide-casein systems, which were heated at 120 degrees C and pH 6.7, were identified and quantified, and the reaction pathways were established. The main reaction routes were (i) sugar isomerization, (ii) degradation of the sugar into carboxylic acids, and (iii) the Maillard reaction itself, in which not only the sugar itself but also its reaction products react with the epsilon-amino group of lysine residues of the protein. Significant differences in reaction mechanism between aldose and ketose sugars were observed. Ketoses seemed to be more reactive in the sugar degradation reactions than their aldose isomers, and whereas the Amadori product was detected as a Maillard reaction intermediate in the aldose-casein system, no such intermediate could be found in the ketose-casein system. The reaction pathways found were put together into a model, which will be evaluated by kinetic modeling in a subsequent paper.
164 citations
TL;DR: Apart from catalyzing the common two-substrate reaction with ketose as donor substrate and aldose as acceptor substrate, transketolase is also able to catalyze a one- substrate reaction utilizing only ketose (xylulose 5-phosphate) as substrate.
40 citations
Patent•
08 Nov 2001
TL;DR: In this article, a method for the production of glycolaldehyde with high specificity is presented, which consists of spraying of aqueous sugar solutions containing from 25 to 80 % of water but preferably 30 to 60 % water, as a fine mist into a reactor held at the between 500 and 600 °C, but preferably between 520 and 560 °C and the condensation of the resulting vaporous product in a surface condenser with optional heat recovery.
Abstract: The present invention provides a method for the production of glycolaldehyde with high specificity. The hydrous thermolysis consists of the spraying of aqueous sugar solutions containing from 25 to 80 % of water but preferably 30 to 60 % water, as a fine mist into a reactor held at the between 500 and 600 °C , but preferably between 520 and 560 °C and the condensation of the resulting vaporous product in a surface condenser with optional heat recovery. The residence time of the vaporous product in the reactor should be in the range 0.1 -5 seconds, but preferably in the range 0.5 to 2 seconds. Aldose monomeric sugars, preferably glucose (also known as dextrose), are preferred for use in the aqueous solution. The yield of glycolaldehyde in the condensed liquid is minimum 50 % by weight of the sugar fed for glucose solutions.
38 citations
24 citations
TL;DR: 13C NMR studies using D-(1-(13)C)glucose and D-galactose with the CaCl(2) system in CD(3)OD revealed that the C-2 epimerization proceeds via stereospecific rearrangement of the carbon skeleton, or 1,2-carbon shift, and ketose formation proceeds partially through an intramolecular hydrogen migration or 1
21 citations
TL;DR: The interaction of transketolase ketosubstrates with the holoenzyme has been studied and changes in the CD spectrum caused by the addition of reversibly or irreversibly cleaving substrates indicate that in both cases the changes are due to the formation of an intermediate product of the transketoase reaction.
Abstract: The interaction of transketolase ketosubstrates with the holoenzyme has been studied. On addition of ketosubstrates cleaving both irreversibly (hydroxypyruvate) and reversibly (xylulose 5-phosphate), identical changes in the CD spectrum at 300-360 nm are observed. The changes in this spectral region, as previously shown, are due to the formation of the catalytically active holoenzyme from the apoenzyme and the coenzyme, and the cleavage of ketosubstrates by transketolase. The identity of the changes in transketolase CD spectrum caused by the addition of reversibly or irreversibly cleaving substrates indicates that in the both cases the changes are due to the formation of an intermediate product of the transketolase reaction—a glycolaldehyde residue covalently bound to the coenzyme within the holoenzyme molecule. Usually, in the course of the transferase reaction, the glycolaldehyde residue is transferred to an aldose (acceptor substrate), resulting in the recycling of the holoenzyme free of the glycolaldehyde residue. The removal of the glycolaldehyde residue from the holoenzyme appears to proceed even in the absence of an aldose. However, the glycolaldehyde cannot be found the free state because it condenses with another glycolaldehyde residue formed in the course of the cleavage of another ketosubstrate molecule yielding erythrulose.
17 citations
TL;DR: The fact that voltage‐gated potassium channel beta subunits that contain aldehyde and aldose reductase‐like NADPH-binding motifs have been detected in plasma membrane fractions of islets suggests that NADPH might have a yet unknown function in regulating activity of these potassium channels.
Abstract: Recent evidence of a pyruvate malate shuttle capable of transporting a large amount of NADPH equivalents out of mitochondria in pancreatic islets suggests that cytosolic NADP(H) plays a role in beta cell metabolism. To obtain clues about these processes the activities of several NADPH‐utilizing enzymes were estimated in pancreatic islets. Low levels of pyrroquinolone quinone (PQQ) and low levels of enzyme activity that reduce PQQ were found in islets. Low activities of palmitoyl‐CoA and stearoyl‐CoA desaturases were also detected. Significant activities of glutathione reductase, aldose reductase (EC.1.1.1.21) and aldehyde reductase (EC.1.1.1.2) were present in islets. Potent inhibitors of aldehyde and aldose reductases inhibited neither glucose‐induced insulin release nor glucose metabolism in islets indicating that these reductases are not directly involved in glucose‐induced insulin reaction. Over 90% of aldose reductase plus aldehyde reductase enzyme activity was present in the cytosol. Kinetic and chromatographic studies indicated that 60–70% of this activity in cytosol was due to aldehyde reductase and the remainder due to aldose reductase. Aldehyde reductase‐like enzyme activity, as well as aldose reductase immunoreactivity, was detected in rat islet plasma membrane fractions purified by a polyethylene glycol‐Dextran gradient or by a sucrose gradient. This is interesting in view of the fact that voltage‐gated potassium channel beta subunits that contain aldehyde and aldose reductase‐like NADPH-binding motifs have been detected in plasma membrane fractions of islets [Receptors and Channels 7: 237–243, 2000] and suggests that NADPH might have a yet unknown function in regulating activity of these potassium channels. Reductases may be present in cytosol to protect the insulin cell from molecules that cause oxidative injury.
15 citations
10 citations
TL;DR: In this paper, a branched-chain aldose, 2-C-(hydroxymethyl)-D-glycero-D-gulo-heptose, was obtained, which was stereospecifically rearranged under the catalytic action of molybdic acid.
Abstract: D-Glycero-D-gulo-heptose reacted with 2,2-dimethoxypropane to give its 2,3:6,7-di-O-isopropylidene derivative. Its base-catalyzed addition to formaldehyde resulted in the formation of 2,3:6,7-di-O-isopropylidene-2-C-(hydroxymethyl)-D-glycero-D-gulo-heptofuranose. After acid hydrolysis of this aldolization product, a new branched-chain aldose, 2-C-(hydroxymethyl)-D-glycero-D-gulo-heptose, was obtained, which was stereospecifically rearranged under the catalytic action of molybdic acid to D-glycero-D-ido-oct-2-ulose.
5 citations
4 citations
Patent•
26 Sep 2001
TL;DR: In this article, a reproducible O-glycoside molecular aggregate is obtained by dissolving an O glycoside comprising an aldose residue as a glycosyl group and a group of general formula (1) (R is a 12-18C aliphatic saturated or unsaturated straight-chain hydrocarbon group) in water at an elevated temperature up to a saturated concentration and then slowly cooling the aqueous solution to cause a molecular aggregation.
Abstract: PROBLEM TO BE SOLVED: To obtain a new reproducible molecular aggregate usable in a wide range producible from a readily obtainable raw material by a simple method. SOLUTION: This fibrous O-glycoside molecular aggregate is produced by dissolving an O-glycoside comprising an aldose residue as a glycosyl group and a group of general formula (1) (R is a 12-18C aliphatic saturated or unsaturated straight-chain hydrocarbon group) as an aglycone in water at an elevated temperature up to a saturated concentration and then slowly cooling the aqueous solution to cause a molecular aggregation. This spherical O-glycoside molecular aggregate is produced by further heating the molecular aggregate and sphering the heated molecular aggregate. This crystal type O-glycoside molecular aggregate is produced by heating an O-glycoside comprising an aldose residue as a glycosyl group and a group of general formula (2) (R is a 12-18C aliphatic saturated or unsaturated straight-chain hydrocarbon group) as an aglycone in the absence of a solvent to cause a crystalline molecular aggregation.
Patent•
26 Sep 2001
TL;DR: In this article, a carboxylic acid type saccharide derivative is represented by the general formula G-NHCO-(CH2)n-COOH (G is an aldose residue after removal of a reducing terminal hydroxyl group and the whole hyroxyl groups existing in the residue are protected; n is an integer of 6-20).
Abstract: PROBLEM TO BE SOLVED: To obtain a glycolipid usable in a wide range as various kinds of functional materials by forming a stable molecular aggregate excellently dispersible in water from a readily obtainable raw material. SOLUTION: This carboxylic acid type saccharide derivative is represented by the general formula G-NHCO-(CH2)n-COOH (G is an aldose residue after removal of a reducing terminal hydroxyl group and the whole hydroxyl groups existing in the residue are protected; n is an integer of 6-20).
Patent•
30 Jul 2001
TL;DR: In this paper, a process for producing hydrazinomonosaccharide derivatives and use of hydrazines in determining the structures of aldose and ketose maccharides located at the reducing ends of saccharides is described.
Abstract: A process for producing hydrazinomonosaccharide derivatives and use of hydrazines in determining the structures of aldose and ketose monosaccharides located at the reducing ends of saccharides.
Patent•
26 Sep 2001
TL;DR: In this article, the problem of obtaining a new O-glycoside type glycolipid simply mass-producible from a readily obtainable naturally occurring substance as a raw material, useful as a functional material was addressed.
Abstract: PROBLEM TO BE SOLVED: To obtain a new O-glycoside type glycolipid simply mass-producible from a readily obtainable naturally occurring substance as a raw material, useful as a functional material. SOLUTION: This O-glycoside type glycolipid comprises an aldose group as a glycosyl group and a group of the general formula (R1 is a hydrogen atom or a hydroxyl group; R2 is a hydrogen atom or a carboxyl group; R3 is an aliphatic saturated or unsaturated straight-chain hydrocarbon group) as an aglycone.
Patent•
18 Jul 2001TL;DR: Salts of Co, Ni or Ru are used as catalysts in the preparation of aldoses and aldose derivatives by treatment of an aqueous solution of a salt of an acid derivative of an ose with H2O2 as discussed by the authors.
Abstract: of EP0908465Salts of Co, Ni or Ru are used as catalysts in the preparation of aldoses and aldose derivatives by treatment of an aqueous solution of a salt of an acid derivative of an ose with H2O2. Process for preparing an aldose (I) or an aldose derivative (II) with n C atoms comprises contacting an aqueous solution of a salt of an acid derivative of an ose (III) with n+2 C atoms and at least one alpha -hydroxyacid group, with the exception of gluconic acid, with H2O2 in the presence of at least one salt of a metal selected from Co, Ni and Ru. Use of salts of Ni, Co or Ru as catalysts in the conversion gives high yields of the desired aldose products and provides a viable route to large scale production of aldose products at reasonable cost.
TL;DR: In this paper, the CaCl2 system was used for the epimerization of aldoses at C-2 by a combination of alkaline-earth or rare-earth metal ions (Ca2+, Sr2+, Pr3+) and such monoamines as triethylamine.
Abstract: Epimerization of aldoses at C-2 has been extensively investigated by using various metal ions in conjunction with diamines, monoamines, and aminoalcohols. Aldoses are epimerized at C-2 by a combination of alkaline-earth or rare-earth metal ions (Ca2+, Sr2+, Pr3+, or Ce3+) and such monoamines as triethylamine. In particular, the Ca2+–triethylamine system proved effective in promoting aldose–ketose isomerization as well as C-2 epimerization of aldoses. 13C NMR studies using d -(1-13C)glucose and d -(1-13C)galactose with the CaCl2 system in CD3OD revealed that the C-2 epimerization proceeds via stereospecific rearrangement of the carbon skeleton, or 1,2-carbon shift, and ketose formation proceeds partially through an intramolecular hydrogen migration or 1,2-hydride shift and, in part, via an enediol intermediate. These simultaneous aldose–aldose and aldose–ketose isomerizations showed interesting substrate-dependent chemoselectivity. Whereas the mannose-type aldoses having 2,3-erythro configuration ( d -mannose, d -lyxose, and d -ribose) showed considerable resistance to both the C-2 epimerization and the aldose–ketose isomerization, the glucose-type sugars having 2,3-threo and 3,4-threo configurations, d -glucose and d -xylose, are mainly epimerized at C-2 and those having the 2,3-threo and 3,4-erythro configurations, d -galactose and d -arabinose, were mostly isomerized into 2-ketoses. These features are of potential interest in relevance to biomimic sugar transformations by metal ions.
TL;DR: In this paper, a branched-chain aldose, 2-C-(hydroxymethyl)-D-glycero-D-gulo-heptose, was obtained, which was stereospecifically rearranged under the catalytic action of molybdic acid.
Abstract: D-Glycero-D-gulo-heptose reacted with 2,2-dimethoxypropane to give its 2,3:6,7-di-O-isopropylidene derivative. Its base-catalyzed addition to formaldehyde resulted in the formation of 2,3:6,7-di-O-isopropylidene-2-C-(hydroxymethyl)-D-glycero-D-gulo-heptofuranose. After acid hydrolysis of this aldolization product, a new branched-chain aldose, 2-C-(hydroxymethyl)-D-glycero-D-gulo-heptose, was obtained, which was stereospecifically rearranged under the catalytic action of molybdic acid to D-glycero-D-ido-oct-2-ulose.