Of n-galacturonic acid

A series of crystalline salts of n-galacturonic acid has recently been prepared by Isbell and Frush. Some of these, e. g., calcium sodium D-galacturonate, are suitable for the separation of n-galacturonic acid from plant materials. 

Acetylation of the formazan of n-galacturonic acid leads to a lactone acetate which has three acetyl groups and is an appropriate starting material for the preparation of the corresponding tetrazolimn compound. 

The formazan reaction, carried out at certain critical rotational values, also permits the interpretation of the structural changes observable during mutarotation of n-galacturonic acid phenylhydrazone (see Fig. 11). 

Fig. 11.— Lower Curve Mutarotation of n-Galacturonic Acid Phenylhydrazone (pyridine-ethanol, 1 1 by vol.) Upper Curve n-Galacturonic Acid Af.AT -Diphenyl-formazan Formation.

L-arabinose molecules combine together in the furanose form to produce an araban. Since enzymes capable of hydrolysing pectic acid to n-galacturonic acid are known to be present in certain plant juices, and since the comparatively low temperature and slightly acid condition of plant materials would tend to favor the transformation of arabinose into the furanose form, the occurrence of the furanose structure in the polysaccharide derived from arabinose is not altogether unexpected. 

N. O. Maness, J. D. Ryan, and A. J. Mort, Determination of the degree of methyl esterification of pectins in small samples by selective reduction of esterified galacturonic acid to galactose, Anal. Biochem., 185 (1990) 346-352. 

Many hemicelluloses are known to consist of n-glucuronic acid, combined with n-xylose, L-arabinose, or both and to contain no hexose. A few hemicelluloses have been reported to contain n-galacturonic acid, n-glucose, n-mannose or n-galactose. - - Since pectic materials and cellulosans often dissolve in the alkaline solution used in extracting the hemicelluloses, it is quite possible that the galacturonic acid and hexoses may be derived from these materials and not from hemicelluloses. 

The methylated galactoses obtained from tamarack galactan were analyzed as the per (trimethylsilyl) derivatives by Jiang and Timell, and the same derivatives were used by Larsson and Samuelson in a study of a galacturonic acid anhydride. 3-O-Methyl-n-galactose has been estimated in the hydrolyzate of a fungal heteropolysaccharide by using trimethylsilyl derivatives. ... 

Simple esters of the sugar acids, as ethyl D-mannonate 102) and diethyl galactarate 103), have long been known (Chapter VI). n-Galacturonic acid occurs in pectins largely esterified with methanol 104), Many of the methyl esters of the 0-acetyl aldonic acids have been obtained by the action of diazomethane upon the fully acetylated aldonic acids. Penta-0-acetyl-D-gluconates of some of the alditols (XVIII) and of cellulose have been described 106), The methyl acid ester of di-0-acetyl-L-(dea ro)-... 

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. 

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