128. Enzymic synthesis and degradation of starch. Part XV. β-Amylase and the constitution of amylose

Peat, Stanley; Pirt, S. J.; Whelan, W. J.

doi:10.1039/jr9520000705

Cited by 60 publications

(31 citation statements)

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“…Some amylose molecules have a few branches per molecule. [3][4][5] In contrast, amylopectin is a type of moderately branched macromolecules with a-(1,4)-linked D-glucosyl chains and $5% of a-(1,6)-linkages. 6 Specific methods for separation of starch components and also starch types may define a third component: the intermediate material, which is structurally intermediate between amylose and amylopectin.…”

Section: Introductionmentioning

confidence: 91%

Branching patterns in leaf starches from Arabidopsis mutants deficient in diverse starch synthases

Zhu

Bertoft

Szydlowski

et al. 2015

Carbohydrate Research

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Section: Introductionmentioning

confidence: 91%

Branching patterns in leaf starches from Arabidopsis mutants deficient in diverse starch synthases

Zhu

Bertoft

Szydlowski

et al. 2015

Carbohydrate Research

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“…[10][11][12][13][14][15][16][17][18][19] The most satis factory one involves complete dispersion of the granules in boiling water (in an inert atmosphere to avoid degradation), followed by precipitation of amylose as an insoluble com plex with substances such as thymol or butanl-ol. This complex can be removed by centrifugation, and the amylose purified by reprecipitation.…”

Section: Introduction Starch During Malting Little Work Has Beenmentioning

confidence: 99%

A Comparison of the Starches From Barley and Malted Barley

Greenwood

Thomson

1959

Journal of the Institute of Brewing

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Starch has been isolated from barley and malted barley of the same sample of cereal. The malted-barley starch had a higher apparent amylose content, a higher gelatinization temperature, and smaller granules than that from the original barley. Pre-treatment of the granules of both starches with liquid ammonia was necessary to achieve complete dispersion prior to fractionation into their component amylose and amylopectin. The amylose from the malted-barley starch was smaller in molecu lar size and had a higher j3-amylolys!s limit than that from the barley. The amylo pectin fractions differed with regard to average chain length and /9-amylolysis limit, but they were of comparable molecular size. Calculation showed the two amylopectins to have similar internal chain-lengths, but different external chain-lengths, that for the malted-barley amylopectin being smaller. This suggests that the maltedbarley amylopectin had been degraded by /9-amylase to a limited extent. Subfractions ofamylose obtained on successive aqueous leaching of both granular starches showed a decrease In jff-amylolysis limit with increase in molecular size. The pro perties of the components from malted-barley starch can be satisfactorily accounted for by assuming limited /3-amylolysis of the amylopectin and very limited a-amylolysis of the amytose in the original barley starch. Introductionstarch during malting, little work has been

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“…Failure of "-amylase to degrade amylose completely (Peat et al 1949(Peat et al , 1952) and the increased "-amylolysis limit of amylose by the cooperative action of "-amylase and debranching enzyme (Kjølberg and Manners 1963;Banks and Greenwood 1966) suggested the presence of '-(1,6)-linkages in the amylose. Disagreements between the DP n determined by the osmotic pressure measurement and by determination of the non-reducing terminal residues by periodate oxidation and the fact that the latter method gives lower DP n values confirmed the presence of '-(1,6)-branches Hassid 1948a, b, 1951).…”

Section: Evidence For the Presence Of Branches In Amylosementioning

confidence: 97%

Fine Structure of Amylose

Hanashiro

2015

Starch

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Amylose is usually the second most abundant component of starch, accounting for typically 20-30 % of its weight. In contrast to the more abundant, highly branched amylopectin, amylose is generally recognized as a linear or slightly branched molecule, both of which are present in amylose prepared from native starch. The structure of amylose can be described in terms of its size and branching. The size of amylose differs depending on the source of the starch, with average degree of polymerization in the range of 1,000 to 5,000. The branching of amylose can be characterized as a whole, or for the branched components by several structural indices, including its "-amylolysis limit (70-90 %), average chain length (200-500), number of chains per molecule (5-20, for the branched molecules), and molar fraction of branched molecule (0.2-0.5). Debranching of amylose with isoamylase and/or pullulanase is incomplete (up to 80 %), but still the size distribution of the debranched product can be informative. The main chain of the debranched product is comparable in size to the native amylose. A small number of long side chains are present with a chain length of from several hundred to a similar length as the main chain. The vast majority of the side chains on a molar basis are short chains, which have a chain-length distribution similar to that of amylopectin. The side chains are not arranged in a cluster fashion, which is a common fundamental structural characteristic of amylopectin. Keywords

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128. Enzymic synthesis and degradation of starch. Part XV. β-Amylase and the constitution of amylose

Cited by 60 publications

References 0 publications

Branching patterns in leaf starches from Arabidopsis mutants deficient in diverse starch synthases

Branching patterns in leaf starches from Arabidopsis mutants deficient in diverse starch synthases

A Comparison of the Starches From Barley and Malted Barley

Fine Structure of Amylose

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