Chitin

Foster, A. B.; Webber, J. M.

doi:10.1016/s0096-5332(08)60192-7

Cited by 55 publications

(28 citation statements)

References 83 publications

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“…7). The specific activity of the chitinase purified on CM- (14,30), and that these walls are readily attacked by glucanase and chitinase (28). We also know that an increase in ethylene production is associated with viral (4,22), bacterial (16), and fungal diseases 8.…”

Section: Resulttsmentioning

confidence: 99%

Preparation and Purification of Glucanase and Chitinase from Bean Leaves

et al. 1971

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Glucanase (endo-0-1,3-glucan 3-glucanohydrolase, EC 3.2.1.6, laminarinase, callase) and chitinase (poly-0-1,4-[2-acetamido-2-deDxyl-D-glucoside glycanohydrolase, EC 3.2.1.14) were extracted from ethylene-treated bean (Phaseolus vulgaris L. cv. Red Kidney) leaves and purified on hiydroxvapatite and carboxymethyl Sephadex columns. The glucanase prepared was homogeneous as judged by anaIlvtical centrifugation data, electrophoresis, and antibodyantigen reactions. On the basis of gel filtration, antibodyantigen reactions, and amino acid analysis, the molecular weight was estimated to be between 11,300 and 12,300. However, ultracentrifugation gave a higher estimate of 34,000. The glucanase had an isoelectric point near pH 11 and was specific for B-1,3-linkages. The chitinase was only partially purified as judged by electrophoretic behavior.Enzyme systems capable of generating (13) and degrading (8) ,B-1 ,3-glucans have been described. The f-1,3-glucans themselves are widespread and have been associated with callose, leaf and stem hairs, root hairs, cystoliths, pollen mother cells, laticifers, pollen grains, pollen tube walls, wounded parenchyma cells (10), ovules (12), development of microspores from tetrads (15), and cell walls (17). fl-1,3-Glucans are also important components of carbohydrate reserves of cereals, algae, and fungi (5).A number of roles have been proposed for glucanase (fl-1,3-glucanase, laminarinase, callase) in plants. These include degradation of seed glucans (11), control of cell elongation (17, 20) (see however 9, 26), regulation of pollen tube growth (25), cell expansion of yeast (27), fertilization (12, 15), and removal of phloem callose (8).In an earlier paper (1), we described an increase in glucanase in ethylene-treated bean leaves that was associated with protein synthesis de novo and correlated with the removal of callose from the phloem. In order to characterize the enzyme more fully and to evaluate the role of the enzyme in the normal phys- iology of the plant, we have selected a purification procedure that resulted in the preparation of electrophoretically pure glucanase. MATERIALS AND METHODS Preparation of Glucanase. Bean (Phaseolus vulgaris L. cv.Red Kidney) leaves (1,300 g) treated for 3 days with 10 ,ul/liter of ethylene (2) were homogenized with 1,400 ml of water in a Waring Blendor. Except where noted, this and subsequent steps were performed at 5 C. The homogenate was filtered through cheesecloth and centrifuged at 10,000g for 10 min, and the precipitate was discarded (step 1). The supernatant was heated to 60 C for 10 min by placing the flask containing the homogenate in a boiling water bath, stirring rapidly, and monitoring the temperature rise until 60 C was reached. The flask was then removed from the bath, cooled slowly at room temperature, and, after 10 min, placed in an ice bath to lower the temperature to 5 C. The denatured protein was removed by centrifuging at 10,000g for 10 min (step 2).The 60 C supernatant was mixed with diethylaminoethyl cellulose (Cellex-D,...

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Section: Resulttsmentioning

confidence: 99%

Preparation and Purification of Glucanase and Chitinase from Bean Leaves

et al. 1971

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“…De fato, após armazenagem em condições de umidade controlada, foi determinado por termogravimetria que a α-quitina apresentava 5-6% de umidade enquanto que 8-12% da massa de β-quitina correspondia à água adsorvida na rede polimérica, o que foi atribuído à menor cristalinidade e morfologia mais favorável de β-quitina 23 . A solubilidade da quitina é restrita a uns poucos sistemas solventes e embora possa ser dissolvida em ácido fórmico anidro (β-quitina) e em soluções concentradas de ácidos fortes, como clorídrico, fosfórico e sulfúrico, a dissolução é muito lenta, tanto de α-como de β-quitina, e provoca severa despolimerização 1, 33,34 . Deve ser ainda ressaltado que no caso da dissolução em ácido sulfúrico além da degradação das cadeias também ocorre O-sulfatação e, portanto, é um derivado da quitina que se solubiliza nesse caso.…”

Section: Figura 2 Representação Esquemática Das Estruturas Polimórfiunclassified

Extração, estruturas e propriedades de alfa- e beta-quitina

et al. 2007

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Recebido em 8/3/06; aceito em 14/6/06; publicado na web em 10/1/07 EXTRACTION, STRUCTURES AND PROPERTIES OF α-AND β-CHITIN. The fact that α-and β-chitin adopt different arrays in the solid state is explored to emphasize their different properties and distinct spectral characteristics and X ray diffraction patterns. The methods for their extraction from the biomass in view of the preservation of their native structures and aiming to fulfill the claims of purity and uniformity for potential applications are discussed. The different arrays adopted by α-and β-chitin also result in distinct reactivities toward the deacetylation reaction. Thus, the deacetylation of β-chitin is more efficient owing to the better accessibility to amide groups due to the lower crystallinity of this polymorph.Keywords: polymorphs; chitin; chitosan. INTRODUÇÃOA quitina foi isolada por Braconnot em 1881, trinta anos antes do isolamento da celulose, mas a falta de conhecimento básico sobre suas propriedades, incluindo a reatividade química, limitou severamente suas aplicações industriais até o início dos anos 1970 1 . A partir de então, o interesse progressivo na química de quitina resultou no desenvolvimento de muitos estudos que visaram aumentar o conhecimento sobre as relações estruturas/propriedades deste polímero e seus derivados. Atualmente, os usos industriais e em larga escala de quitina ainda são muito menos importantes que os de celulose, mas alguns importantes segmentos do mercado já são ocupados por derivados de quitina. A quitosana, por ex., é um polímero muito versátil com aplicações nas indústrias cosmética 2 e alimentícia 3 e que a mais de 25 anos é empregado como agente de floculação no tratamento de efluentes aquosos 4 . Sua capacidade de interagir com variada gama de substâncias, tais como proteínas, lipídeos, pesticidas, corantes, íons metálicos e radioisótopos, qualifica a quitosana para aplicações voltadas tanto para detecção e análise dessas substâncias como para sua concentração ou recuperação 1,5 . Além disso, a quitosana exibe atividade antimicrobiana e devido a sua atoxicidade, biocompatibilidade e biodegradabilidade também tem grande potencial para aplicações na agricultura, em medicina, odontologia e formulações farmacêuticas 1,[5][6][7][8][9][10] . As possibilidades de aplicações são ainda enriquecidas pelo fato que a quitosana pode ser preparada em diferentes formas, tais como soluções de viscosidade controlada, géis, filmes e membranas, microesferas e nanopartículas.Nos últimos 40 anos foram realizados muitos estudos que demonstraram haver uma estreita relação de dependência entre as características estruturais e morfológicas de quitina, quitosana e seus derivados, suas propriedades e aplicações potenciais. De fato, o interesse comercial nas aplicações de quitosana e derivados aumentou vertiginosamente nas últimas três décadas, o que pode ser constatado pelo depósito de patentes no Japão, Europa, China, Coréia e, principalmente, nos EUA. Assim, conforme o "United States Patent and Trademark Office", foram regi...

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“…Before trying to understand the research that has been done on the dietary influence of chitin we note that, "it is doubtful whether a pure, undegraded product is normally obtained" (Foster and Webber, 1960). Even worse, for us, as mycologists, almost all studies have been done with arthropod chitin, it has been said that there is a difference between arthropod and fungal chitin, yet little difference has ever been shown between purified materials from the two sources (Foster and Webber, 1960).…”

Section: Structure-fibersmentioning

confidence: 99%

“…Even worse, for us, as mycologists, almost all studies have been done with arthropod chitin, it has been said that there is a difference between arthropod and fungal chitin, yet little difference has ever been shown between purified materials from the two sources (Foster and Webber, 1960). As we have said, both would be expected to be degraded, so the differences may be lost in preparation.…”

Section: Structure-fibersmentioning

confidence: 99%

Nutrition from mushrooms, understanding and reconciling available data

Kurtzman¹

1997

Mycoscience

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Mushrooms are nutritionally valuable foods. They are high in proteins, including most essential amino acids and high in most water soluble vitamins and probably in pro-vitamin D. However, there have been many reports suggesting that they had little or no value. While the reports of little value were erroneous, other reports have claimed greater nutritional value than can be substantiated, Moreover, most of our knowledge of the nutritional value of mushrooms is based on chemical analysis. Some of the nutrients may be destroyed or unavailable to consumers. This paper looks at the available information and tries to reconcile it.

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Chitin

Cited by 55 publications

References 83 publications

Preparation and Purification of Glucanase and Chitinase from Bean Leaves

Preparation and Purification of Glucanase and Chitinase from Bean Leaves

Extração, estruturas e propriedades de alfa- e beta-quitina

Nutrition from mushrooms, understanding and reconciling available data

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