Studies on Wheat Endosperm III. Galactose-Rich Polysaccharides

JMares, D; Stone, BA

doi:10.1071/bi9731005

Cited by 11 publications

(8 citation statements)

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“…This fractionation procedure has been used by other workers (Preece and Hobkirk 1953;Mares and Stone 1973c) to partially separate polysaccharides enriched in galactose from the arabinoxylans in water extracts of wheat, and the results of Preece and Hobkirk (1953) suggest that galactose-rich polysaccharides may be widely distributed in cereal grains. Similarly, results presented here (Table 8) indicate that ryegrass and barley may also contain polymers of comparable composition to the arabinogalactan-peptide from wheat endosperm.…”

Section: Discussionmentioning

confidence: 99%

A Water-soluble Arabinogalactan-Peptide From Wheat Endosperm

Fincher¹,

Stone²

1974

Aust. Jnl. Of Bio. Sci.

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149

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The water-soluble polymeric components of wheat endosperm have been extracted by two different procedures and their chemical composition studied in detail. Water extracts of wheat flour that had first been treated with hot 80% ethanol contained only 2% protein, but if the ethanol treatment was omitted up to 20% of the extracted polymeric fraction was low-molecular-weight non-dialysable protein material. Density-gradient ultracentrifugation in caesium chloride solutions indicated that most of this protein was free, whereas the 2% protein in the water extract of ethanol-treated flottr was firmly bound to a polysaccharide. This bound protein (a peptide) was characterized by high levels of hydroxyproline (16-20% of the amino acids present).Fractional precipitation of the water-soluble components with ammonium sulphate enabled the separation of a high-molecular-weight arabinoxylan (xylose : arabinose = 1·6 -1 . 9) and a lowmolecular-weight arabinogalactan (galactose :. arabinose =approx. 1· 5), the latter. being associated with the hydroxyproline-rich peptide.

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Section: Discussionmentioning

confidence: 99%

A Water-soluble Arabinogalactan-Peptide From Wheat Endosperm

Fincher¹,

Stone²

1974

Aust. Jnl. Of Bio. Sci.

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149

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“…WE PEN include WE arabinoxylans (AX) and arabinogalactan peptide (AGP). The latter is probably, unlike the AX, not closely related with cell walls (Mares and Stone, 1973c;Fincher and Stone, 1974). The WU NSP consist of AX, which represent the major part (Mares and Stone, 1973a), -D-glucan, cellulose, and glucomannan.…”

Section: Introductionmentioning

confidence: 98%

Distribution and Structural Variation of Arabinoxylans in Common Wheat Mill Streams

Delcour

Win

Grobet

1998

J. Agric. Food Chem.

105

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In 19 wheat-milling fractions total pentosan content, calculated as 0.88 x (% L-arabinose + % D-xylose), varied between 1.44 and 30.66% on dry matter (dm). It increased with ash content once the latter exceeded 0.6% (dm basis). Water-extractable arabinoxylans were recovered by saturating water extracts to 65% ethanol. Their contents in the milling fractions varied between 0.35 and 1.38%, and above 0.6% ash content also increased with this parameter. Their L-arabinose-to-D-xylose ratios ranged between 0.65 and 0.39, with the lowest values found for the fractions with highest ash content, indicating that the ash-rich tissues contain more arabinoxylans that are less branched. (1)H NMR spectroscopy revealed that the decrease in L-arabinose-to-D-xylose ratio was accompanied by an increase in unsubstituted xylose residues and a decrease in disubstituted xylose residues, while the contents of monosubstituted xyloses were virtually constant.

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“…Total pentosans are usually divided into water-soluble or water-insoluble fractions. Waterinsoluble pentosans are typically associated with cell walls, whereas water-soluble pentosans are found interior to endosperm cell walls, probably in association with membranes (Mares and Stone 1973). This association of pentosans with amyloplast membranes may serve to modify starch-protein matrix adhesion and therefore have an effect on texture.…”

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confidence: 99%

Relationships Among Grain Hardness, Pentosan Fractions, and End‐Use Quality of Wheat

2000

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Cereal Chem. 77(2):241-247Grain texture (hardness) in wheat (Triticum aestivum L.) is a major determinant of end-usage. Variation in grain texture can be conceptually assigned to the two major hardness classes that result from the action of one major gene (Hardness) or to as-yet undetermined factors contributing to residual variation within hardness classes. Identifying the physicochemical basis of both sources of texture variation could provide a means of better controlling or manipulating this quality trait. Pursuant to this objective, the role of pentosans was examined. Pentosan fractions (membrane-associated, total, and soluble) were isolated from 13 hard and 13 soft wheat samples and their flours. Among the hard wheat samples, pentosans had a minimal role in modifying grain hardness. However, among the soft wheat samples, pentosans appeared to have a significant hardness-modifying effect that carried over into end-use quality. Among the soft wheat samples, pentosan fractions, along with wheat protein, accounted for 53-76% of the variation in grain texture, depending on the method used to quantify texture. Membrane-associated pentosans were the most influential single parameter in modeling grain texture for the soft wheat samples. Membrane-associated pentosans were most influential in accounting for variation (69%) in alkaline water retention capacity. Total pentosans, together with flour protein, accounted for 87% of the variation in cookie diameter for soft wheat samples, with the total pentosan fraction being the more influential.

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Studies on Wheat Endosperm III. Galactose-Rich Polysaccharides

Abstract: Galactose-rich polysaccharides have been found in the finely divided material passing 75-JLm nylon-mesh sieves during the isolation of wheat endosperm cell walls in 70 % aqueous ethanol.

Cited by 11 publications

References 0 publications

A Water-soluble Arabinogalactan-Peptide From Wheat Endosperm

A Water-soluble Arabinogalactan-Peptide From Wheat Endosperm

Distribution and Structural Variation of Arabinoxylans in Common Wheat Mill Streams

Relationships Among Grain Hardness, Pentosan Fractions, and End‐Use Quality of Wheat

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