L-Galacturonic acid

Acetamido-2-deoxy-D-galacturonamide, A-212 2-Acetamido-2-deoxy-D-galacturonic acid, A-212 2-Acetamido-2-deoxy-L-galacturonic acid, A-212 2-Acetamido-2-deoxy-4-0-a-D-glucopyranosyl-D-mannopyranuronic acid,... 

Oxidations with nitric acid under the best conditions convert primary alcoholic and aldehydic groups to carboxylic groups. Frequently, however, cleavage of carbon-carbon bonds occurs. For galactose the conversion to insoluble mucic acid, COOH—(CHOH)4—COOH, takes place to an extent greater than 70 %, and the reaction is used for the quantitative determination of this sugar (229, 230). This oxidation has been halted before completion and a 10% yield of the L-galacturonic acid obtained (231). Smaller... 

Pectin belongs to a family of plant polysaccharides in which the polymer backbone consists of (1— 4)-linked a-D-galacturonic acid repeating-units. Often, (1— 2)-linked a-L-rhamnose residues interrupt the regular polygalacturonate sequence. The high viscosity and gelling properties of pectins are exploited by the food and pharmaceutical industries. X-Ray studies on sodium pectate, calcium pectate, pectic acid, and pectinic acid (methyl ester of pectic acid) have disclosed their structural details. 

The LPS from Proteus species contain amino acids linked as amides to acidic sugars. Thus, L-lysine is linked by way of N-6 to a D-galacturonic acid residue (52) in the LPS from P. hauseri, but by way of N-2 to a D-glucu-ronic acid residue in the LPS from P. mirabilis 027. The latter LPS also contains L-alanine, linked to the carboxyl group of a D-galacturonic acid residue. 

The DE were determined by titrimetry, and the galacturonic acid (GalA) content was measured by the m-hydroxybiphenyl method [25]. The structural charge density parameter introduced by Lifson and Katchalsky [26], is given by = e2/bDkT(l-DE/100) were e is the electron charge, kT the Boltzman term, b... 

Figure 2. Potential energy maps of a) GalA(l->2)Rha as a function of the glycosidic dihedrals, b) the same disaccharide with the galacturonic acid acetylated at 02 and 03. The conformation used to build integer helices is indicated.

The glycosyl-residue compositions of the three purified fractions (Table 1) were very similar with a predominance of galacturonic acid, rhamnose and arabinose. The presence in the three purified fractions of the rare monosaccharides characteristic of RG-II (e.g. 2-( -methyl-L-fucose, 2-O-methyl-D-xylose, apiose, Kdo, Dha and aceric acid) was confirmed by GC-CIMS analysis. The molar ratios corresponded approximately to the known structure of the RG-II molecule (Figure 1) and to previously published data for RG-II from sycamore [26], rice [4], arabidospis leaves [8] and Pectinol [12]. 

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