Uronic acids, fractionation

Figure 3. Size-exclusion chromatography on Biogel P4 of fraction IPN obtained after anion-exchange chromatography. Fractions (2.5 ml each) were pooled as indicated. — - neutral sugars, — uronic acid. Fractions 1, 2, 3. .. were named later as fractions IPN 1, IPN 2, IPN 3. .. respectively.

The sole component of the uridine diphosphate uronic acid fraction from animal tissues,10,124,139 Chlorella,4 red algae,83 and some bacteria118,119 is uridine 5 -(a-D-glucopyranosyluronic acid pyrophosphate) (32), whereas a similar preparation from Pneumococcus140 contains only the a-D-galactopyranosyluronic acid derivative. Both esters have been shown to occur in extracts of mung bean.141,142... 

Recently, the alkah-soluble hemicelluloses of hardwood dissolving pulps have been investigated [28]. Their composition and molecular properties depended on the pulp origin and steeping conditions. The MGX of the j8-fraction from press lye had a low uronic acid content (ratio of MeGlcA to Xyl is about 1 20). The molecular weight of the hemicellulose fractions varied between 5000 and lOOOOg/mol. 

Figure 3. Anion-exchange chromatography on DEAE Sepharose of fraction I of the Sephacryl S300 fractionation of a) saponified MHR population A after degradation with RGase and after b) degradation of the non-saponified MHR population A with RGase and RGAEase ---------, uronic acid —, neutral sugars thin line, NaOAc gradient [39],...

Fig. 1. Promotion of ethylene synthesis by MG pericarp discs following treatment with water or varying concentrations (uronic acid equivalents) of B fruit water soluble fraction. Bars indicate SEs for the means of measurements of sets of 8 discs/teatment fr wt, Fresh weight.

Fig. 3. QAE-Sephadex gradient separation of the B fruit extract. An 18 mg (uronic acid equivalents) sample of extract was dissolved in 20 ml of 125 mM imidazole-HCl buffer (pH 7.0) and applied to the column. The column was then eluted with 50 ml 125 mM buffer followed by a 125 mM to 1.5 M buffer gradient (500ml), and, finally, 50 ml of 1.5 M buffer. Fractions of 5 ml were collected and assayed for uronic acids. Groups of fractions (26-41, 45-50, 53-75 and 84-100) were pooled, concentrated by ultrafiltration and analyzed by HPLC.

The AIS of fresh and canned carrots were sequentially fractionated into water-soluble pectin (WSP), oxalate-soluble pectin (OXSP), acid-soluble pectin (HSP), alkah-soluble pectin (OHSP), hemicellulose and cellulose. The distribution of uronic acid among various fractions is presented in Table 1. WSP of fresh carrots accounted for 19.0% of the total pectin, while OXSP constituted 29.6%. HSP represented the lowest (12.0%) pectin fraction, whereas OHSP was the highest (35.6%) In the hemicellulose and cellulose fractions significant amounts of uronic acid were found. Heat treatments during canning altered the proportion... 

Distribution of uronic acid in the fractions of the alcohol insoluble... 

Effect of CaCk on the distribution of uronic acid in the fractions of alcohol insoluble solids of carrots canned by conventional and by a new process (as mg AUA/100 g fresh weight)... 

ChSS was fractionated on a column (550 x 15 mm) of DEAE Sepharo e Fast Flow using a Hiload System (Pharmacia), which was initially equilibrated in 0.005 M NaAc-bufFer pH 5.0. The sample was dissolved in water, the insoluble residue was removed by centrifugation and the supernatant was applied onto the column. After applying the gradient shown in Figure 1, the residual polysaccharides were washed from the column using 0.5 M NaOH. Fractions (23 ml) were collected and assayed by automated methods [2,3] for total neutral sugars and uronic acids. 

ChSS and DASS were rich in arabinose, galactose and uronic acids. These were, as expected, pectin-rich extracts and had a very similar sugar composition. The 1 MASS fraction was also rich in arabinose, galactose and uronic acids, but next to that it is also enriched in... 

The floss silk from Chorisia speciosa furnished a polysaccharide with a main chain of (1 -> 4) linked P-Xylp substituted at 0-2 by 5 % of uronic acid. The xylan structure also was interposed with a-Rhap units in small amounts. The defatted seeds furnished on aqueous extraction a major fraction, ((9-acetyl, 10 % and protein, 45 %) wich was hydrolysed and analysed by p.c. and GLC, showing Rha (20 %), Ara (16 %), Gal (64 %) and also uronic acids (45 %). Partial hydrolysis gave rise to a polysaccharide free of arabinose, with 46 % of uronic acids. Methylation analysis (GLC -MS) indicated a chain of (1 4) - linked Gal/ (42 % of 2,3,6-Me3-Gal). 

Rha, Ara and Gal are the neutral sugar components from all the fractions. Xyl is not present in Fla and is significantly present in the hemicellulose fractions, indicating that this monosaccharide is component of hemicellulosic polymers. Chemical composition of the water fractions were determined (Table V). High protein contents and the presence of O-acetyl-groups were observed in four aqueous fractions. Neutral sugar and uronic acid composition points to inclusion of these polymers in the class of pectic polysaccharides. 

Table V. Determination of carbohydrates, proteins, uronic acids and 0-acetyl of Fractions from aqueous extractions from seeds of C. speciosa.

Neutral sugars increased in the water soluble fraction and didn t change on imidazole and carbonate ones. Uronic acids, on the other hand increased in the imidazole fraction and decreased in both water and carbonate ones. 

Neutral sugar, uronic acid and methylation analysis (mol%) of fractionated pectins from ripe red beets... 

Ratio of PMAA derivatives of uronic acids and neutral sugars in fraction N1... 

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