Uronic acid 1972 Volume

Marsh grapefhiit (MGF) pulp was homogenized in 5 volumes of extraction buffer at 4 C and maintained at pH 8.0 (28). The homogenate was stirred for one hour, centrifuged and the supernatant used as the PE extract. Activity was measured by titration with a Brinkman (Westbury, NY) pH stat titrator at pH 7.5 and 30°C in 25 mL of 1 % high methoxyl pectin (Citrus Colloids Limited, Hereford, UK) with O.IM NaCl. PE units are expressed as the microequivalents of ester hydrolysed per minute. Uronic acid analyses were conducted based on the m-phenyl phenol (4) as modified for microplate reading (30). 

Substrate buffer 1.657 mg 4-methylumbelliferyl-a-L-(idopyranosid)-uronic acid-sodium salt (6.6 mM Toronto Research Chemicals) is dissolved in 333 pi demineralized water. The same volume of reaction buffer is added and the solution is vor-texed for 30 s. The substrate buffer is stored at -20°C and protected from light. 

Feingold DS (1982) Aldo (and Keto) hexoses and uronic acids. In Loewus FA, Tanner W (eds) Encyclopedia of plant physiology New Series Volume 13A Carbohydrates I Intracellular Carbohydrates. Springer, Berlin Heidelberg New York, p 3... 

When 1.5 volumes acetone is added to the trichloroacetic acid filtrate of the gastric juice, an abundant flocculent precipitate forms, which contains all the components of dissolved mucin with the exception of soluble mucus. If this precipitate is taken up in dilute alkali and then acidified with dilute HCl down to pH 3.5, a fine flocculent precipitate forms, which we named dissolved mucoprotein (G27, G36). It was later renamed glandular mucoprotein (G9, G38) because of its close relationship to the fundic glands of the stomach. This material contained much protein its nitrogen content was 12.61 0.44% and its tyrosine content 7.50 0.65% by the Folin-Giocalteu reaction. The reducing substance content was 6.38 1.48% before and 12.5% after hydrolysis (G9, G27, G36) (see Table 4). Werner (W9) determined the composition of this mucoprotein fraction and found that it contained 11.2% N by Kjeldahl, 8.8% hexosamine, 4.8% uronic acid, and 2.0% sialic acid. 

Uronic Acid Composition and Block Length. A sample containing 75 mg alginic acid was first suspended in a small volume of D2O, then fully neutralized by titration with 1.0 M NaOD. D2O was added to achieve a final concentration of 25 mg alginic acid/mL D2O. Equilibration of at least one hour was allowed prior to NMR acquisition. The uronic acid composition was determined by NN spectroscopy, with a 2 s pulse repetition time and 16,000 scans. The reported composition and block lengths were the average of two determinations. 

Figure 4. Gel filtration of a pectate lyase degraded pectin. AUA = anhydro-uronic acid content, Ve = elution volume, the eluent was water.

In an attempt to correlate gross structure of solute-water with packing and stereochemistry, the partial molal volumes and isentropic partial molal compressibilities were measured for sugars, uronic acids, and some di- and trisaccharides in water at 25 C. Attempts to systematize the results were unsuccessful. In a different approach, the structural transitions at saturation temperature using Arrhenius plots of results obtained by conductance measurements on electrolyte-sucrose-water solution were determined. These transitions were postulated to be due to the ability of the sucrose to form intermolecular hydrogen bonds with the solvent, so that at saturation temperature it was considered to have entered the total structure of the solution. ... 

Equal volumes of a and b are mixed as required. Heated 5—10 min in a drying oven at 100—105 C (for ketoses) or 10—15 min on the water bath in a moist atmosphere at 70— 80 C (uronic acids). Any collidine or pyridine present interferes with the colour reaction. Resorcinol, orcinol, phloroglucinol or a-naphthol may be used instead of the naphthoresorcinol. The trichloroacetic acid solution may be replaced by a tenth of its volume of 85% phosphoric acid. 

Details of a number of established chemical methods used in determining various aspects of the fine structures of polysaccharides-for example, the specific degradation of polysaccharides containing uronic acid residues by base-catalysed elimination, the location of acyl substituents, and the distribution of singleunit side-chains of D-galactose in galactomannans by alkaline hydrolysis of 6-deoxy-6-(4-tolylsulphonyl)hexopyranosides -are reported in the latest volume in the series Methods in Carbohydrate Chemistry . 

Procedure A few milligrams of uronic acid are dissolved in 4 ml of HCl and 4 ml of water, and the mixture is boiled for a few moments 4 ml of the clear solution are mixed with 100 mg of naphthoresorcinol and the mixture is boiled again for 30 min, then cooled and extracted with an equal volume of benzene the benzene layer assumes a violet color. 

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