The Chemistry of Polysaccharides of Fungi and Lichens

Gorin, Philip A.J.; Barreto‐Bergter, Eliana

doi:10.1016/b978-0-12-065602-8.50011-x

Cited by 42 publications

(15 citation statements)

References 284 publications

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“…8) The high-field values at 63.8 ppm and 63.5 ppm could be assigned to C-6 of P-D-galactofuranosyl residues [22,27], and would confirm the presence of two chemical environments for this monosaccharide. ~4 1 .…”

Section: Specific Rotationmentioning

confidence: 82%

d‐Galactofuranose in the N‐linked sugar chain of a glycopeptide from Ascobolus furfuraceus

Groisman¹,

Lederkremer²

1987

European Journal of Biochemistry

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Two types of linkages between the carbohydrate and the peptide moiety in the glycopeptide from AscoboIus furfuraceus are described. Treatment with mild alkali produced /I-elimination of a small oligosaccharide. Evidence for the 0-glycosidic linkage was provided by (a) increase in absorbance at 240 nm, (b) decrease in threonine and serine content after the alkaline treatment and (c) detection of tritiated oligosaccharide following alkaline NaB3H4 reduction. Mannose is the sugar involved in the 0-glycosidic linkage. The remaining glycopeptide was branched by galactofuranose units, which were selectivity released by mild acid hydrolysis. The N-glycosidic linkage of the sugar chain was conclusively proved by cleavage with endo-P-N-acetyl-glucosaminidase. Sequential NaB3H4 reduction and acid hydrolysis gave [3H]glucosaminitol. The structure of the sugar chain was studied by 13C NMR spectroscopy and by methylation analysis.Galactomannans with galactose in the furanoid configuration are produced by many fungi where they occur either as constituents of the cell wall or as exocellular polysaccharides Terminal galactofuranosyl units were found responsible for the antigenic properties and for cross-reactions of the immunologically active glycans [6, 71. However, in only a few examples was a peptide linkage to the sugar chain established.The isolation and preliminary structural studies of a galactofuranosyl-containing glycopeptide from Ascobolus furfuraceus have been reported [S]. The glycopeptide has a relative molecular mass of about 20000 and contains mannose, galactose, glucose and glucosamine. The molar proportions of neutral sugars varied when glycopeptides from different cultures were analysed. The variable percentages of galactose, which is mainly present as terminal furanoid units, branching a backbone of mannoses, may reflect the action of an exo-,6-D-galactofurdnosidase as in the case of the glycopeptide from Penicillium charlesii [9]. This variability would have no influence on the general structure of the oligosaccharide chains nor on the type of linkages to the peptide.Glucose was always a minor component and in some samples only traces were detected. Also two units of glucosamine per mole of glycopeptide were analysed.In this paper we report the presence of galactofuranosyl units branching a N-linked polysaccharide in the glycopeptide from the fungus A. furfuraceus. The structure of the carbohydrate moiety was studied by 13C NMR spectroscopy, methylation and periodate oxidation studies.[l -51. EXPERIMENTAL PROCEDURE MaterialsCultures were obtained from single ascospores of A. furfuraceus strain C-233 [lo]. The glycopeptide was isolated and purified from a 13 -14-day culture as previously reported [8].[14C]Formaldehyde labeling of the glycopeptide was carried out as described [8]. Andy t ical met hodsOptical rotations were determined with a Perkin-Elmer 141 polarimeter. A Beckman DU spectrometer was used for the ultraviolet and visible determinations. GLC was conducted with a Hewlett-Packard 5830 A gas chroma...

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Section: Specific Rotationmentioning

confidence: 82%

d‐Galactofuranose in the N‐linked sugar chain of a glycopeptide from Ascobolus furfuraceus

Groisman¹,

Lederkremer²

1987

European Journal of Biochemistry

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“…The H-1/C-1 region (Fig. 3) showed the presence of six correlated signals and the two main ones at N 5.06/98.1 and 4.98/98.9 suggest the presence of substituted units of 6-O-and 2,6-di-O-substituted K-Manp units, respectively [11]. A signal of a non-reducing end was also observed at N 4.60/103.0, which suggested L-Galp units along the polysaccharide structure.…”

Section: Resultsmentioning

confidence: 99%

Studies on neutral exopolysaccharides produced by the ectomycorrhiza Thelephora terrestris

Osaku¹

2002

FEMS Microbiology Letters

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The ectomycorrhizal hymenomycete Thelephora terrestris was grown in synthetic pure culture and the production of extracellular polysaccharide was monitored. The exopolysaccharides were prepared by ethanol precipitation and then fractionated into two components using a DEAE^Sepharose column. A neutral fraction (NeP) was fractionated on Sepharose CL-6B, which resulted in three peaks: NeP1, NeP2 and NeP3. NeP1 was filtered through an exclusion membrane and two polysaccharides were obtained (fractions: NeA, NeB). Fraction NeB was submitted to methylated derivatives and 1 H-, 13 C-and 2D NMR spectroscopic analyses. These analyses showed a main chain of a (1C6)

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“…Esta técnica baseia-se na observação de que núcleos magnéticos tais como 1 H, 13 C, 31 P e 15 N podem absorver energia em freqüências características, quando colocados em um campo magnético forte. A freqüência de ressonância de um núcleo particular, expressa como deslocamento químico (δ), é sensível ao ambiente químico da molécula, tornando o RMN uma técnica valiosíssima para estudos estruturais 43,44 . Cada molécula tem um espectro de RMN característico que pode ser usado como uma impressão digital ("fingerprint") da mesma.…”

Section: Caracterização Química Das Glucanas Fúngicasunclassified

Caracterização química de glucanas fúngicas e suas aplicações biotecnológicas

Silva¹,

Martinez²,

Izeli³

et al. 2006

Quím. Nova

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Recebido em 28/9/04; aceito em 27/4/05; publicado na web em 24/8/05 CHEMICAL CHARACTERIZATION AND BIOTECHNOLOGY APPLICATIONS OF FUNGAL GLUCANS. This article gives an overview of exopolysaccharides produced by fungi. The structural characterization of β-D-(1→3) and β-D-(1→3, 1→6)-glucans is discussed focusing on different chemical and physical procedures. The industrial applications are also considered mainly from the point of view of human health.Keywords: exopolysaccharides; glucans; structural characterization. INTRODUÇÃOOs biopolímeros têm sido objeto de intensa pesquisa, tendo em vista seu elevado potencial de aplicação em diferentes setores 1 . Os polissacarídeos de origem microbiana além de apresentarem propriedades similares ou superiores aos tradicionais (de origem vegetal e algas marinhas) são, muitas vezes, capazes de formar soluções viscosas. Alguns deles também formam géis em meio aquoso, mesmo em baixas concentrações e, em alguns casos, esses polímeros são utilizados como substratos para desenvolvimento de novos produtos, por ex., após uma derivatização química 2 . A produção de exopolissacarídeos (EPS) microbianos não se encontra exposta às alterações climáticas, à contaminação marinha ou à problemas nas colheitas, que prejudicam a oferta e alteram o custo de produção das gomas tradicionais 3 . São, ainda, menos susceptíveis à variabilidade em suas propriedades químicas e físicas, mantendo o padrão de qualidade, pois sua produção pode ser controlada cuidadosamente; além disso, sua recuperação e purificação apresentam dificuldades menores, comparadas aos vegetais, como também há técnicas de genética molecular que permitem obter polissacarídeos microbianos com propriedades específicas, as quais ainda não são possíveis 4,5 nos vegetais. Vários EPS microbianos já são aceitos como produtos biotecnológicos e, embora apresentem muitas vantagens, o custo de produção para a maioria deles ainda é relativamente alto quando comparado àqueles obtidos de vegetais e algas marinhas, devido aos processos de produção, intensivos investimentos em capital e energia. Assim, existem poucos microrganismos que produzem EPS com rendimentos satisfatórios para desenvolvimento em escala industrial e, conseqüentemente, sua exploração comercial ainda é baixa. Entretanto, para alguns polímeros, a relação custo/benefí-cio justifica a produção, por possuírem propriedades químicas e físicas únicas ou superiores às dos polissacarídeos tradicionais 3,6 , como por ex., a alta viscosidade, o maior poder geleificante, a compatibilidade com uma grande variedade de sais em ampla faixa de pH e temperatura, a estabilidade em elevadas concentrações iônicas, a alta solubilidade em água e, também, a ação sinérgica com outros polissacarídeos 7 . Todas estas propriedades são diretamente dependentes das características químicas, físicas e estruturais de cada polímero, como massa molecular (número de unidades por molécula), configuração anomérica (α ou β), conformação (linear, ramificada, helicoidal, agregação entre cadeias), presença de grupament...

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The Chemistry of Polysaccharides of Fungi and Lichens

Cited by 42 publications

References 284 publications

d‐Galactofuranose in the N‐linked sugar chain of a glycopeptide from Ascobolus furfuraceus

d‐Galactofuranose in the N‐linked sugar chain of a glycopeptide from Ascobolus furfuraceus

Studies on neutral exopolysaccharides produced by the ectomycorrhiza Thelephora terrestris

Caracterização química de glucanas fúngicas e suas aplicações biotecnológicas

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