Selective chemical depolymerization of rhamnogalacturonans

Pectic substances: From simple pectic polysaccharides to complex pectins—A new hypothetical model

“…They can, however, account for 50-90% (w/w) of most extracted pectins and encompass more than 80% of the pectin GalA residues (Table 1), thus highlighting their overwhelming majority in pectic substances. However, unbranched HGs have been found in low amounts in pectins from potato tubers (Øbro, Harholt, Scheller, & Orfila, 2004) and soybean cotyledons (Nakamura et al, 2002a), and almost absent in water-solubilised mucilages from Arabidopsis thaliana and Linum usitatissimum seeds (Deng, O'Neill, & York, 2006;Muralikrishna, Salimath, & Tharanathan, 1987;Naran, Chen, & Carpita, 2008). Unsubstituted HGs are likely to be homogenous in size within a given plant material (Fig.…”

“…The glycosyl residue composition of RGs-I depends on pectin source and isolation method. Although a relatively unbranched RG-I has been characterised from seedcoat mucilage of A. thaliana (Deng et al, 2006;Penfield, Meissner, Shoue, Carpita, & Bevan, 2001), RGs-I are generally highly ramified polysaccharides having a backbone made up of the repeating disaccharide [→2)-␣-l-Rhap-(1 → 4)-␣-d-GalpA-(1→] n ≥ 1 , partly substituted, at O-4 (mainly) and/or O-3 (scarcely) positions of ␣-l-Rhap residues, with single neutral glycosyl residues and polymeric side chains of different types, viz. (1 → 5)-␣-l-arabinans, (1 → 4)-␤-d-galactans, arabinogalactans-I (AG-I), arabinogalactans-II (AG-II), and possibly galacto-arabinans (Øbro et al, 2004;Tharanathan, Reddy, Muralikrishna, & Susheelamma, 1994;Yapo, 2007).…”

Enzymatic Solubilisation and Degradation of Soybean Fibre Demonstrated by Viscosity, Fibre Analysis and Microscopy

“…It should be noted that Arabidopsis thaliana seed coat mucilage consists largely of unbranched rhamnogalacturonan although with homogalacturonan elements (Deng et al, 2006). The solubilisation of pectin by the commercial product, as visualized by loss of coriphosphine O orange color ( Figures 2C-2D and 2G-2H) as well as loss of epitopes binding to antibody LM20, may actually indicate the presence of rhamnogalacturonase in the product ( Figure 3A) since soybeans are assumed to not contain homogalacturonan (Huismann et al, 2001).…”

Structural analysis of an innate immunostimulant from broccoli, <i>Brassica oleracea</i> var. <i>italica </i>

“…Before the methylation reaction, galacturonic acid in the sample was methyl-esterified, and reduced to (6,6-dideutero)galactose using NaBD 4 as described previously (11). Methylation of the polysaccharide was performed according to the Ciucanu method using sodium hydroxide and CH 3 I (12).…”