d-galacturonic acid

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d-ga·lac·tu·ron·ic ac·id

(gă-lak-tūr-on'ik as'id),
The d-isomer is an oxidation product of d-galactose, in which the 6-CH2OH group has become a -COOH group; occurs in many natural products (for example, pectins) and cell walls.
Synonym(s): pectic acid
References in periodicals archive ?
These enzymes can hydrolyze protopectins and pectins to smaller chains like galacturonic acid (Sun et al., 2006), leading to a reduction of water holding capacity.
Usually, pectin contains 65% galacturonic acid and may show three kinds of forms: the linear homopolygalacturonan and the ramified, rhamnogalacturonan I and II (WILLATS et al., 2006).
Sugar composition of fractions C and D was analyzed by the methylation method (McGarvie and Parolis, 1981), confirming the presence of arabinose, xylose, galactose, rhamnose and galacturonic acid. The total amount of monosaccharides contained in fractions C and D was determined by a "two-step" process consisting in an initial hydrolysis of polysaccharidic structures and in the quantification of monosaccharide content (expressed as rhamnose) in the hydrolysed fractions by the phenol-sulphuric acid test (Dubois et al., 1956; Mankarios et al., 1979).
Total uronic acids were estimated colorimetrically by means of galacturonic acid as the calibration standard (Ahmed and Labavitch, 1977).
Phytochemical reports on Ziziphus species has revealed the presence of polysaccharides (Yamada et al., 1985; Zhao et al., 2006a), a pectin composed of D- galacturonic acid, L-rhamnose, D-galacturonic acid as methyl ester and O-acetyl groups (Shimizu and Tomoda, 1983), cyclopeptides (Barboni et al., 1994; Gournelis et al., 1998; Singh et al., 2002), peptide alkaloids (Tschesche et al., 1974), flavonoides (Nawar et al., 1984; Cheng et al., 2000), dodecaacetylprodelphinidin B3 (Weinges and Schick, 1995), Ziziphine N, O, P and Q (Suksamrarn et al, 2005), saponins and fatty acids (Zhao et al., 2006b).
The analyses were calibrated against galacturonic acid and the absorbance measured at 400 and 450 mm to determine the difference in absorbance due to uronic acids.
Polygalacturonase is a de-polymerizing enzyme which catalyze [alpha]-1,4 glycosidic linkage in pectin chain to yield galacturonic acid units (Kim et al., 2017).
The calibration curve was conducted with D- galacturonic acid, and the PG activity was expressed as mmoL of galacturonic acid per gram of dry weight per minute (mmoL [g.sup.-1] [min..sup.-1]).
The standard monosaccharides mannose (Man), rhamnose (Rha), glucuronic acid (GlcA), galacturonic acid (GalA), glucose (Glc), galactose (Gal), xylose (Xyl), arabinose (Ara) and fucose (Fuc) were all purchased from Sigma.
(1956) and expressed as g of glucose 100 [g.sup.-1]; d) soluble and total pectins: extracted according with McCready and McComb (1952) and quantified through the Bitter and Muir (1962) technique, the results being expressed as % galacturonic acid 100 [g.sup.-1].