Showing papers on "Aldose published in 1997"
TL;DR: The acidic hydrolysis and fluorophore labeling conditions described in this paper are suitable for monosaccharide composition analysis of a wide variety of complex carbohydrates from glycoprotein and/or oligosacchcharide samples using capillary electrophoresis.
120 citations
TL;DR: The three-dimensional structure of L-fucose isomerase from Escherichia coli has been determined by X-ray crystallography at 25 A resolution.
78 citations
TL;DR: Based on the crystal structure of this complex a reaction mechanism for transaldolase is proposed, and the overall structures of the complex and the native enzyme are very similar.
Abstract: Transaldolase catalyzes transfer of a dihydroxyacetone moiety from a ketose donor to an aldose acceptor. During catalysis, a Schiff-base intermediate between dihydroxyacetone and the epsilon-amino group of a lysine residue at the active site of the enzyme is formed. This Schiff-base intermediate has been trapped by reduction with potassium borohydride, and the crystal structure of this complex has been determined at 2.2 A resolution. The overall structures of the complex and the native enzyme are very similar; formation of the intermediate induces no large conformational changes. The dihydroxyacetone moiety is covalently linked to the side chain of Lys 132 at the active site of the enzyme. The Cl hydroxyl group of the dihydroxyacetone moiety forms hydrogen bonds to the side chains of residues Asn 154 and Ser 176. The C3 hydroxyl group interacts with the side chain of Asp 17 and Asn 35. Based on the crystal structure of this complex a reaction mechanism for transaldolase is proposed.
65 citations
TL;DR: It is proposed that interactions of inhibitors with the carboxy-terminal loop of aldose reductase are critical for the development of inhibitors that are able to discriminate between aldoses reductases and other members of the aldo-keto reduct enzyme superfamily.
Abstract: It is generally expected that only one inhibitor molecule will bind to an enzyme active site. In fact, specific drug design theories depend upon this assumption. Here, we report the binding of two molecules of an inhibitor to the same active site which we observed in the 1.8 A resolution structure of the drug Alrestatin bound to a mutant of human aldose reductase. The two molecules of Alrestatin bind to the active site in a stacked arrangement (a double-decker). This stack positions the carboxylic acid of one drug molecule near the NADP+ cofactor at a previously determined anion binding site and the carboxylic acid of the second drug molecule near the carboxy-terminal tail of the enzyme. We propose that interactions of inhibitors with the carboxy-terminal loop of aldose reductase are critical for the development of inhibitors that are able to discriminate between aldose reductase and other members of the aldo-keto reductase superfamily. This finding suggests a new direction for the introduction of specificity to aldose reductase-targeted drugs.
49 citations
TL;DR: In this paper, the seven-coordinated cage-type cobalt-II complexes containing N-glycosides from mannose-type aldoses and tris(2-aminoethyl)amine (tren), where (aldose)3tren is tris (2-(aldosylamino)ethyl)amines, were prepared and characterized by elemental analysis, electronic absorption and circular dichroism spectroscopies, and X-ray crystallography.
Abstract: Novel seven-coordinated cage-type cobalt(II) complexes containing N-glycosides from mannose-type aldoses and tris(2-aminoethyl)amine (tren), [Co((aldose)3tren)]X2·nH2O (1a·5H2O, aldose = d-mannose (d-Man), X = Cl-; 1b·5H2O, aldose = 6-deoxy-l-mannose (l-Rha), X = Cl-; 2a·4H2O, aldose = d-Man, X = Br-; 2b·H2O, aldose = l-Rha, X = Br-) and [Co((aldose)3tren)]SO4·nH2O (3a·4H2O, aldose = d-Man; 3b·3H2O, aldose = l-Rha), where (aldose)3tren is tris(2-(aldosylamino)ethyl)amine, were prepared and characterized by elemental analysis, electronic absorption and circular dichroism spectroscopies, and X-ray crystallography. Crystal data are as follows. 2b·2CH3OH: C26H56N4O14Br2Co, monoclinic, space group P21, a = 11.045(2) A, b = 17.283(6) A, c = 10.996(3) A, β = 117.371(6)°, V = 1864(1) A3, Z = 2, R = 0.072 for 2787 independent reflections. 3b·3H2O·CH3OH: C25H58N4O20SCo, orthorhombic, space group P212121, a = 14.836(2) A, b = 22.489(2) A, c = 12.181(3) A, V = 4064(1) A3, Z = 4, R = 0.077 for 2010 independent refle...
35 citations
TL;DR: In this paper, the 1-phenyl-3-methyl-5-pyrazolone derivatives of aldose enantiomers were well separated from each other by capillary zone electrophoresis using a neutral phosphate buffer containing an optically active N-dodecoxycarbonylvaline (DCV).
33 citations
TL;DR: The results show that DHMA is normally a minor metabolite of NE, but becomes a major metabolite after aldehyde/aldose reductase inhibition, and is also increased in brain tissue levels of DHMA.
Abstract: After norepinephrine (NE) is deaminated by monoamine oxidase (MAO), the aldehyde formed is either metabolized to 3,4-dihydroxymandelic acid (DHMA) by aldehyde dehydrogenase or is converted to 3,4-dihydroxyphenylglycol (DHPG) by aldehyde or aldose reductase. The present study examined the effects of inhibition of aldehyde and aldose reductase on production of DHPG and DHMA in rats. Mean (±S.E.) baseline plasma concentrations of DHPG (4.73±0.21 pmol/ml) were 60-fold higher than those of DHMA (0.08±0.01 pmol/ml). Inhibition of aldose and aldehyde reductase reduced plasma DHPG concentrations to 1.88±0.14 pmol/ml and increased plasma DHMA to 4.43±0.29 pmol/ml; additional inhibition of MAO reduced plasma DHPG to 0.16±0.06 pmol/ml and DHMA to 0.19±0.02 pmol/ml. Inhibition of aldehyde and aldose reductase also increased brain tissue levels of DHMA from 8±2 to 384±47 pmol/g and decreased levels of DHPG from 70±9 to 44±5 pmol/g. The results show that DHMA is normally a minor metabolite of NE, but becomes a major metabolite after aldehyde/aldose reductase inhibition.
27 citations
TL;DR: The acidophilic and thermophilic red alga Galdieria sulphuraria is able to grow heterotrophically on at least six different pentoses through an NADP-dependent aldose reductase and the activity of the enzyme with hexoses, deoxysugars, and sugar phosphates was low and only detectable with pentiols.
Abstract: The acidophilic and thermophilic red alga Galdieria sulphuraria is able to grow heterotrophically on at least six different pentoses. These pentoses are reduced in the cell to pentiols by an NADP-dependent aldose reductase. The pentiols are then introduced into the oxidative pentose phosphate pathway via NAD-dependent polyol dehydrogenases and pentulokinases. The aldose reductase was purified 130-fold to apparent homogeneity by column chromatography. The enzyme is a homodimer of about 80 kD, as estimated by size-exclusion chromatography and from the sedimentation behavior. The Michaelis constant values for D-xylose (27 mM), D-ribose (29 mM), D-lyxose (30 mM), and D-arabinose (38 mM) were about three to five times lower than for the L-forms of the sugars. The activity of the enzyme with hexoses, deoxysugars, and sugar phosphates was only about 5 to 10% of the rate with pentoses. In the reverse reaction the activity was low and only detectable with pentiols. No activity was measured with NAD(H) as the cosubstrate in either direction.
15 citations
TL;DR: In this article, a new type of poly(vinyl sugar) is described whose polymer backbone is connected with the monosaccharide unit by a C-C bond.
Abstract: The synthesis of a new type of poly(vinyl sugar) is described whose polymer backbone is connected with the monosaccharide unit by a C-C bond. Such polymers can be obtained by radical initiation. They show good stability in polymer-analogous reactions in contrast to common poly(vinyl saccharides) whose sugar residues are bound to the polymeric chain by ester, ether, or glycoside bonds. Starting from 7,8-dideoxy-1,2;3,4-di-O-isopropylidene-a-D-galacto-oct-7-en-1,5-pyranos-6-ulose (1) polymers (P1) could be obtained by emulsion polymerization in high yields. Reduction of the keto group of P1 proceeded quantitatively and yielded poly(7,8-dideoxy-1,2;3,4-di-O-isopropylidene-D,L-g1ycero-a-D-ga1acto-oct-7-en-l,5-pyranose) (P3). In contrast to the following polymers without protecting groups these poly(vinyl ketones), which were soluble in tetrahydrofuran and toluene, did not follow a pure GPC-separation mechanism. The protecting groups of the poly(vinyl saccharides), either with or without keto groups, could be removed completely to give P2 and P4. The solubility of the polymers P2 with galactose-functionalized side chains in water was limited to a weight-average molecular weight M ω of 1500000 due to association phenomena of the monosaccharide units. Reduction of the hemiacetal group and of the keto group of P2 yielded poly(1,2-dideoxy-D,L-glycero-D-galacto-oct- I -enitol) (P5) with sugar alcohol side chains instead of a cyclic monosaccharide unit. Oxidation of the hemiacetal group of P2 and P4 furnished poly(7,8-dideoxy-D-galacto-oct-7-en-6-ulosonic acid sodium salt) (P6) and poly(7,8-dideoxy-D,L-glycero-D-galacto-oct-7-enonic acid sodium salt) (P7), respectively. These polymers showed very high viscosities because of their polyelectrolyte character.
14 citations
TL;DR: In this article, enantiomeric pairs of trifluoroacetylated alditols or aldose diethyl dithioacetals were separated using capillary columns containing chiral stationary phases of permethylated α-cyclodextrin (α-Dex 120), β-Cycle-Dextrin(β-Dex 60), γ-Cyclodex(γ-Dex 90), and γ -Cycle(γ)-Cycle (γ-DEX 120).
10 citations
Journal Article•
TL;DR: In this paper, the configurational switch around the seven-coordinate manganese center ligated by a cage-type N-glycoside ligand was found to depend on its counter anion by X-ray crystallographic analyses of [Mn(aldose3-tren]X2 (2: aldose = D-mannose, X = Br; 4: anion = L-rhamnose X = 1 2 SO 4 ), where n-aldosyl-2-aminoethyl)amine is tris(
TL;DR: In this article, a preparation of a D-glucose analogue in which the 4-hydroxyl group can be replaced by radioactive iodine is presented, and the preparation is shown to work well in the presence of radioactive iodine.
Abstract: A preparation of a D-glucose analogue in which the 4-hydroxyl group can be replaced by radioactive iodine is presented.
Journal Article•
TL;DR: The equilibrium constants of the primary binding of both the initial and produced ketose and also the initial aldose were unequivocally determined by varying the initial substrate concentrations, confirming the hypothesis of flip-flop functioning of the transketolase active sites.
Abstract: A kinetic model of bisubstrate reaction catalyzed by baker's yeast transketolase is proposed. The model considers individual stages of substrates reversible primary binding. The model corresponds to the observed kinetics of product accumulation within a wide range of initial substrate concentrations. Kinetic parameters for the best simulation of the experimental data are defined. The equilibrium constants of the primary binding of both the initial and produced ketose and also the initial aldose were unequivocally determined by varying the initial substrate concentrations. The dissociation constants of the primary enzyme-substrate complex for the initial ketose (xylulose 5-phosphate) and the reaction product (sedoheptulose 7-phosphate) were found to differ by more than by two orders of magnitude. The result is discussed in the context of the hypothesis of flip-flop functioning of the transketolase active sites.
Patent•
26 Nov 1997TL;DR: In this article, the process for producing an aldose or aldoses derivative containing n carbon atoms is described, which involves: (a) contacting an aqueous solution of a sugar acid having n+1 carbon atoms and containing at least one alpha-hydroxy acid unit, or a salt thereof, with hydrogen peroxide in the presence of a copper salt; (b) separating precipitated copper; (c) regenerating the copper salt with the corresponding acid; and (d) recycling the regenerated salt.
Abstract: Process for producing an aldose or aldose derivative containing n carbon atoms comprises: (a) contacting an aqueous solution of a sugar acid having n+1 carbon atoms and containing at least one alpha -hydroxy acid unit, or a salt thereof, with hydrogen peroxide in the presence of a copper salt; (b) separating precipitated copper; (c) regenerating the copper salt with the corresponding acid; and (d) recycling the regenerated salt. The aqueous solution contains 1-60 wt.% of the sugar acid. The Cu salt is used in an amount of 0.01-50% based on the sugar acid. The H2O2 has a concentration of 35-70% and is used in an amount of 1-500 mole% based on the sugar acid. The reaction is effected at 0-100 deg C, especially 15-40 deg C, and pH 5-9, especially 6-8. The sugar acid is arabinonic acid, optionally in Na or Ca salt form. The copper salt is CuSO4 and is regenerated with H2SO4.
Patent•
27 Jun 1997
TL;DR: For example, Copolymers containing 1 - 99% of groups of formula (I) -O-CH(R)-CO-X-CO, X-CO-- and at least 1% of the functional groups in R-CHOH-COOH derived from an ose are preferred as discussed by the authors.
Abstract: Biodegradable copolymers containing groups of formula (I) derived from an aldose or ketose and groups of formula (II) derived from a hydroxy acid. Copolymers containing 1 - 99% of groups of formula (I) --O-CH(R)-CO-X-CO-- and at least 1% of groups of formula (II) --O-L-CO-- R = the residue of an acid R-CHOH-COOH derived from an ose, the functional groups in R optionally being substituted;X = -C(R1)(R2)- or -C(R1)(R2)-C(R3)(R4)-;R1, R2, R3, R4 = H, alkyl, allyl, aryl, or aralkyl;L = the residue of a hydroxy acid HO-L-COOH selected from those capable of forming a dilactone or monolactone ring Copolymers in which the group R is derived from an aldonic, uronic, or erythronic acid are preferred, especially those where L is derived from an aldonic, 5-hydroxy pentanoic or 6-hydroxy hexanoic acid.
TL;DR: Synthesis of Glycosaminoglycan-Like Copolysaccharide Derivative and the System of Anhydroglucosamine Monomer and Carboxyl-Containing Monomer has a Tendency to Alternate.
Abstract: Synthesis of Glycosaminoglycan-Like Copolysaccharide Derivative. The System of Anhydroglucosamine Monomer and Carboxyl-Containing Monomer Has a Tendency to Alternate
01 Jan 1997
TL;DR: D-xylose isomerase is one of the most widely used industrial enzymes and requires Mg2+, Co2+ or Mn2+ for activation while other divalent cations inhibit catalysis.
Abstract: D-xylose isomerase (EC 5.3.1.5) catalyses the reversible conversion of D-xylose to D-xylulose and is also capable of converting other sugars from aldose to ketose [1]. It is the latter activity on glucose and fructose, that accounts for the fact that it is one of the most widely used industrial enzymes. It is active in oligomeric forms and requires Mg2+, Co2+ or Mn2+ for activation while other divalent cations, e.g Zn2+, Ba2+ Cu2+ and Ca2+ inhibit catalysis [2]. The effect of the latter cation is of practical importance since a preceding enzyme in the starch bioconversion process, α-amylase, is only active in the presence of calcium ions, the removal of which requires an ion exchange step.
Journal Article•