hemicellulose

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/05/22 21:52:12」(JST)

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A hemicellulose (Also known as Polyose) is any of several heteropolymers (matrix polysaccharides), such as arabinoxylans, present along with cellulose in almost all plant cell walls. While cellulose is crystalline, strong, and resistant to hydrolysis, hemicellulose has a random, amorphous structure with little strength. It is easily hydrolyzed by dilute acid or base as well as myriad hemicellulase enzymes.

Most common molecular motif of hemicellulose

Composition [edit]

Hemicelluloses include xylan, glucuronoxylan, arabinoxylan, glucomannan, and xyloglucan.

These polysaccharides contain many different sugar monomers. In contrast, cellulose contains only anhydrous glucose. For instance, besides glucose, sugar monomers in hemicellulose can include xylose, mannose, galactose, rhamnose, and arabinose. Hemicelluloses contain most of the D-pentose sugars, and occasionally small amounts of L-sugars as well. Xylose is in most cases the sugar monomer present in the largest amount, although in softwoods mannose can be the most abundant sugar. Not only regular sugars can be found in hemicellulose, but also their acidified form, for instance glucuronic acid and galacturonic acid can be present.

Structural comparison to cellulose [edit]

Unlike cellulose, hemicellulose (also a polysaccharide) consists of shorter chains – 500–3,000 sugar units as opposed to 7,000–15,000 glucose molecules per polymer seen in cellulose. In addition, hemicellulose is a branched polymer, while cellulose is unbranched.

Native structure [edit]

Section of a cell wall; hemicellulose in green

Hemicelluloses are embedded in the cell walls of plants, sometimes in chains that form a 'ground' - they bind with pectin to cellulose to form a network of cross-linked fibres.

Biosynthesis [edit]

Hemicelluloses are synthesised from sugar nucleotides in the Golgi. Two models explain their synthesis: 1) a ‘2 component model' where modification occurs at two transmembrane proteins, and 2) a '1 component model' where modification occurs only at one transmembrane protein. After synthesis, hemicelluloses are transported to the plasma membrane via golgi vesicles.

Applications [edit]

As percent content of hemicellulose increases in animal feed, the voluntary feed intake decreases.

Hemicellulose is represented by the difference between neutral detergent fiber (NDF) and acid detergent fiber (ADF).

Functions [edit]

Microfibrils are cross-linked together by hemicellulose homopolymers. Lignins assist and strengthen the attachment of hemicelluloses to microfibrils.

Hemicellulose from trees [edit]

Hemicellulose found in hardwood trees is predominantly xylan with some glucomannan, while in softwoods it is mainly rich in galactoglucomannan and contains only a small amount of xylan. The average molecular weight is lower than that of cellulose at less than 30,000, as opposed to the 100,000 average molecular weight reported for cellulose.

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1. 胃石 gastric bezoars

English Journal

Study of "napier grass" delignification for production of cellulosic derivatives.

de Araújo Morandim-Giannetti A, Albuquerque TS, de Carvalho RK, Araújo RM, Magnabosco R.SourceDepartamento de Engenharia Química, Centro Universitário da FEI, Av. Humberto de Alencar Castelo Branco, 3972, 09850-901 São Bernardo do Campo, SP, Brazil. Electronic address: andreia.morandim@gmail.com.
Carbohydrate polymers.Carbohydr Polym.2013 Jan 30;92(1):849-55. doi: 10.1016/j.carbpol.2012.09.095. Epub 2012 Oct 8.
Recently, much research on the evaluation of new cellulose sources has been developed. In this context, a promising source is "napier grass", which contains 30.40% lignin, 36.34% cellulose, and 34.12% hemicellulose. In this work, conditions for the delignification of "napier grass" in the laboratory
PMID 23218375

Chemical and functional properties of cell wall polymers from two cherry varieties at two developmental stages.

Basanta MF, de Escalada Plá MF, Stortz CA, Rojas AM.SourceDepartamento de Química Orgánica-CIHIDECAR, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
Carbohydrate polymers.Carbohydr Polym.2013 Jan 30;92(1):830-41. doi: 10.1016/j.carbpol.2012.09.091. Epub 2012 Oct 8.
The cell wall polysaccharides of Regina and Sunburst cherry varieties at two developmental stages were extracted sequentially, and their changes in monosaccharide composition and functional properties were studied. The loosely-attached pectins presented a lower d-galacturonic acid/rhamnose ratio tha
PMID 23218373

Japanese Journal

小麦フスマヘミセルロースとグアーガムの長期摂取が高脂肪食投与C57BL/6Jマウスの血中糖・脂質成分と内臓脂肪蓄積に及ぼす影響

江頭祐嘉合,渡辺和輝,平井静 [他]
ルミナコイド研究 : 日本食物繊維学会会誌 18(1), 19-24, 2014-07
NAID 40020187730

重質炭素資源の高効率転換法に関する研究(学会賞(学術部門))

前一廣
日本エネルギー学会誌 93(5), 353-360, 2014-05-20
… On the other hand, the author has been also developed a new method for separating hemicellulose, cellulose and lignin from biomass to efficiently utilize for a thermo-chemical conversion of each component. …
NAID 110009818948

キシログルカン分解酵素に関する研究(受賞論文)

矢追克郎
応用糖質科学 : 日本応用糖質科学会誌 4(1), 32-38, 2014-02-20
様々なキシログルカン分解酵素の探索と性状解析を行うとともに,構造機能相関の解析を行った。Geotrichum sp. M128株由来の2種類のキシログルカン分解酵素においては,XEGはエンド型の酵素,OXG-RCBHはキシログルカンオリゴ糖の還元性末端特異的なエキソ型の酵素で,それぞれ側鎖構造を特異的に認識していることを明らかにした。Paenibacillus sp. KM21株由来の2種類のエン …
NAID 110009804491