20248-27-5Relevant articles and documents
Expanding the reaction space of aldolases using hydroxypyruvate as a nucleophilic substrate
De Berardinis, Véronique,Guérard-Hélaine, Christine,Darii, Ekaterina,Bastard, Karine,Hélaine, Virgil,Mariage, Aline,Petit, Jean-Louis,Poupard, Nicolas,Sánchez-Moreno, Israel,Stam, Mark,Gefflaut, Thierry,Salanoubat, Marcel,Lemaire, Marielle
supporting information, p. 519 - 526 (2017/08/14)
Aldolases are key biocatalysts for stereoselective C-C bond formation allowing access to polyoxygenated chiral units through direct, efficient, and sustainable synthetic processes. The aldol reaction involving unprotected hydroxypyruvate and an aldehyde offers access to valuable polyhydroxy-α-keto acids. However, this undescribed aldolisation is highly challenging, especially regarding stereoselectivity. This reaction was explored using, as biocatalysts, a collection of aldolases selected from biodiversity. Several enzymes that belong to the same pyruvate aldolase Pfam family (PF03328) were found to produce the desired hexulosonic acids from hydroxypyruvate and d-glyceraldehyde with complementary stereoselectivities. One of them was selected for the proof of concept as a biocatalytic tool to prepare five (3S,4S) aldol adducts through an eco-friendly process.
Oxidation of carbohydrates of biological importance by the aquachromium(IV) ion
González, Juan Carlos,Mangiameli, María Florencia,Asis, Agostina Crotta,Bellú, Sebastián,Sala, Luis F.
, p. 84 - 92 (2013/03/28)
The oxidation reactions kinetics of a series of related saccharides by aqua-oxo chromium(IV) ion, (H2O)5CrIVO 2+, were carried out in perchloric acid aqueous solutions. These reactions yield superoxochromium(III) ion, CrO22+, providing evidence that the two-electron reduction of CrO2+ to Cr2+ occurred in a single step. In all of these reactions, Cr 2+ is the immediate product and could be trapped as CrO 22+ when an excess of oxygen was present. The bimolecular rate constants for different aldoses and d-glucitol are independent of [H +] in the range 0.1-1.0 M. Relative reactivities of these saccharides toward CrO2+ reduction are 1-methyl-α-d-glucopyranose 2+ showed the same mechanism but the redox process is strongly inhibited when [H+] increases. Activation parameters were also determined for selected reactions. On the basis of the kinetic result, activation parameters data and oxidized organic products, the mechanism of saccharides oxidation by CrO2+ is proposed to be a direct hydride-ion transfer.
Monosaccharide-H2O2 reactions as a source of glycolate and their stimulation by hydroxyl radicals
Maksimovi?, Vuk,Mojovi?, Milo?,Vu?ini?, ?eljko
, p. 2360 - 2369 (2007/10/03)
An analysis of the H2O2-induced breakdown and transformation of different keto-monosaccharides at physiological concentrations reveals that glycolate and other short-chained carbohydrates and organic acids are produced. Depletion of monosaccharides and glycolate synthesis occurs at increased rates as the length of the carbohydrate chain is decreased, and is significantly increased in the presence of trace amounts of Fe2+ ions (10 μM). Rates of monosaccharide depletion (initial concentration of 3 mM) observed were up to 1.55 mmol h-1 in the case of fructose, and 2.59 mmol h-1 in the case of dihydroxyacetone, depending upon pH, H2O2 concentration, temperature and the presence or absence of catalytic amounts of Fe2+. Glycolate was produced by dihydroxyacetone cleavage at rates up to 0.45 mmol h-1 in the absence, and up to 1.88 mmol h-1 in the presence of Fe2+ ions (pH 8). Besides glycolate, other sugars (ribose, glyceraldehyde, glucose), glucitol (sorbitol) and organic acids (formic and 2-oxogluconic acid) were produced in such H2O2-induced reactions with fructose or dihydroxyacetone. EPR measurements demonstrated the participation of the {radical dot}OH radical, especially at higher pH. Presence of metal ions at higher pH values, resulting in increased glycolate synthesis, was accompanied by enhanced hydroxyl radical generation. Observed changes in intensity of DEPMPO-OH signals recorded from dihydroxyacetone and fructose reactions demonstrate a strong correlation with changes in glycolate yield, suggesting that {radical dot}OH radical formation enhances glycolate synthesis. The results presented suggest that different mechanisms are responsible for the cleavage or other reactions (isomerisation, auto- or free-radical-mediated oxidation) of keto-monosaccharides depending of experimental conditions.
