Uronic Acid


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Related to Uronic Acid: hyaluronic acid, Aldonic acid

uronic acid

[yə′rän·ik ′as·əd]
(organic chemistry)
One of the compounds that are similar to sugars, except that the terminal carbon has been oxidized from the alcohol to a carboxyl group; for example, galacturonic acid and glucuronic acid.

Uronic Acid

 

any of the organic substances that are related to monosaccharides but that are distinguished from the latter by having a carboxyl group (—COOH) in place of the—CH2OH radical. The difference is illustrated by the following structural formulas:

Uronic acids are crystalline or amorphous substances that are nonvolatile, relatively high-melting, and readily soluble in water and polar solvents. Chemically, they possess the properties of both monosaccharides (mutarotation, oxidation, reduction, ability to form glycosides) and hydroxy acids (formulation of esters and lactones). Uronic acids occur in nature with six carbon atoms, and their names are based on the corresponding hexose. The name “glucuronic acid,” for example, derives from “glucose.”

Uronic acids are constituents of many important biopolymers of plant and animal origin. D-glucuronic acid is a component of hemicelluloses, gums, hyaluronic acid, and heparin; D-galacturonic acid, which is the monomeric unit of pectic substances, is a constituent of certain bacterial polysaccharides. The biosynthesis of uronic acids occurs with the participation of nucleoside diphosphate sugars and involves the oxidation of the—CH2OH radical of the monosaccharide. In animals, D-glucuronic acid (found in the blood and urine) removes toxic substances by forming glycosides; the acid is also the starting material in the biosynthesis of absorbic acid.

REFERENCE

Khimiia uglevodov. Moscow, 1967. Chapter 10.

L. V. BAKINOVSKII

References in periodicals archive ?
Sample Total carbohydrate (%) Uronic acid (%) Protein (%) RGP1 92.0 [+ or -] 1.3 4.2 [+ or -] 0.3 ND RGP2 73.1 [+ or -] 1.5 13.6 [+ or -] 0.4 ND RGP3 80.0 [+ or -] 0.5 17.8 [+ or -] 0.6 ND RGP4 72.4 [+ or -] 0.3 8.4 [+ or -] 0.6 ND ND = not detected.
Soluble and insoluble dietary fibre monomers in the raw material and faeces were characterized using GLC for analysis of neutral sugars and spectrophotometry for analysis of uronic acids [33].
Chondroitinases (chondroitinase AC-II, ABC, etc.) are very useful for the determination of GAG structures that are sulfated at various positions.41) Therefore, at the non-reducing terminus of a GAG chain, it is necessary to change unsaturated uronic acid to saturated uronic acid.
A gas chromatographic method for the determination of aldose and uronic acid constituents of plant cell wall polysaccharides.
Principal Component 3 accounted for 16.2% of the variation and was negative for xylose and positive for glucose and uronic acids. Principal Component 4 accounted for 9.1% of the variation and was negative for uronic acids.
Barrett, "Combined enzymatic and colorimetric method for determining the uronic acid and methylester content of pectin: application to tomato products," Food Chemistry, vol.
This acidic nature indicates that the mucilage contains uronic acids in its structure.
The investigators used size exclusion chromatography analysis, carbohydrate analysis and uronic acid assay profiling of the collected fractions to determine the differences between the middle lamella and cell wall pectin.
Uronic acid polysaccharide components were measured colorimetrically in an aliquot from the first step of the acid-hydrolysis procedure using galacturonic acid as the calibration standard (Ahmed and Labavitch, 1977).
Yield (% delignified Fraction material) Extracted with DMSO 9.65 Extracted with NaOH 11.03 Table 2: The contents of neutral sugars and uronic acid (relative%, w/w) of hemicellulosic fractions obtained from DMSO-extracted and NaOH-extracted hemicelluloses.