Determination of Acetyl in Pectin and in Acetylated Carbohydrate Polymers

McComb, E. A.; McCready, R. M.

doi:10.1021/ac60125a025

Cited by 272 publications

(94 citation statements)

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“…Content of total carbohydrates, proteins, uronic acids and acetyl groups was quantified by previously described methods (Blumenkrantz & Asboe-Hansen, 1973;Bradford, 1976;Dubois et al, 1956;McComb & McCready, 1957). In order to avoid interferences due to the presence of heavy metals in the samples, 0.1 M EDTA was added to samples and standards when appropriate.…”

Section: Methodsmentioning

confidence: 99%

Dominance of sphingomonads in a copper-exposed biofilm community for groundwater treatment

et al. 2007

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The structure, biological activity and microbial biodiversity of a biofilm used for the removal of copper from groundwater were studied and compared with those of a biofilm grown under copper-free conditions. A laboratory-scale submerged fixed biofilter was fed with groundwater (2.3 l h "1 ) artificially polluted with Cu(II) (15 mg l "1 ) and amended with sucrose (150 mg l "1 ) as carbon source. Between 73 and 90 % of the Cu(II) was removed from water during long-term operation (over 200 days). The biofilm was a complex ecosystem, consisting of eukaryotic and prokaryotic micro-organisms. Scanning electron microscopy revealed marked structural changes in the biofilm induced by Cu(II), compared to the biofilm grown in absence of the heavy metal. Analysis of cell-bound extracellular polymeric substances (EPS) demonstrated a significant modification of the composition of cell envelopes in response to Cu(II). Transmission electron microscopy and energy-dispersive X-ray microanalysis (EDX) showed that copper bioaccumulated in the EPS matrix by becoming bound to phosphates and/or silicates, whereas copper accumulated only intracytoplasmically in cells of eukaryotic microbes. Cu(II) also decreased sucrose consumption, ATP content and alkaline phosphatase activity of the biofilm. A detailed study of the bacterial community composition was conducted by 16S rRNA-based temperature gradient gel electrophoresis (TGGE) profiling, which showed spatial and temporal stability of the species diversity of copper-exposed biofilms during biofilter operation. PCR reamplification and sequencing of 14 TGGE bands showed the prevalence of alphaproteobacteria, with most sequences (78 %) affiliated to the Sphingomonadaceae. The major cultivable colony type in plate counts of the copper-exposed biofilm was also identified as that of Sphingomonas sp. These data confirm a major role of these organisms in the composition of the Cu(II)-removing community. INTRODUCTIONCopper is an essential trace element for all species studied to date, including humans (Fraga, 2005). However, a large excess intake of Cu(II) in drinking water can cause nausea, gastric irritation and vomiting, while long-term copper intoxication generates liver disease and severe neurological defects in humans (Hotz et al., 2003;Uriu-Adams & Keen, 2005). Chronic ingestion of drinking water with high Cu(II) concentrations (over 3 mg l 21 ) is thus a potential health risk, especially for susceptible populations like children ( Abbreviations: DGGE, denaturing gradient gel electrophoresis; EDX, energy-dispersive X-ray microanalysis; EPS, extracellular polymeric substances; LOI, loss on ignition; SEM, scanning electron microscopy; TEM, transmission electron microscopy; TGGE, temperature gradient gel electrophoresis; UPGMA, unweighted pair grouping with arithmetic averages. input in freshwaters is generated from a number of anthropogenic activities (Cameron, 1992), where these ions sequentially accumulate in sediments, bacteria, tubicid worms and fish, followed by uptake by humans thro...

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Section: Methodsmentioning

confidence: 99%

Dominance of sphingomonads in a copper-exposed biofilm community for groundwater treatment

et al. 2007

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“…The acetyl content was determined with the hydroxamic acid 160 method (McComb & McCready, 1957). The degree of acetylation (DA) was 161 calculated from the galacturonic acid and acetyl content values determined above 162 according to the following equation: 163 DA (%) = 176 x acetyl content (% (w/w)) 43 x GA content (% (w/w)) x 100 (2) 164 where 176 and 43 are the molecular weights of anhydrous galacturonic acid (GA) and 165 acetyl, respectively.…”

Section: Voragen 2009) 93mentioning

confidence: 99%

Isolation and characterization of acetylated LM-pectins extracted from okra pods

2015

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48 49Pectin was isolated by aqueous extraction at pH 6.0 or 2.0 from okra 50 (Abelmoschus esculentus L.) pods. An isolation protocol was designed to extract 51 pectin and to study the influence of the extraction pH on their composition and 52 physicochemical properties. The extracted pectin was assessed using sugar 53 compositional analysis (neutral sugars, galacturonic acid, acetyl and methyl contents). 54FT-IR and NMR spectroscopy, size exclusion chromatography (SEC) and dilute 55 solution viscometry were also used to determine the macromolecular characteristics of 56 isolated pectin. The extraction protocols resulted in the isolation of pectin of high 57 purity as evidenced by their high total carbohydrate (70.0 -81.8%) and low protein 58 (4.3 -6.3%) contents. Samples contained between 46-56% galacturonic acid, had 59 broad molecular weight distributions, a low degree of methylation (40.0 and 24.6 %) 60 and high degree of acetylation (52.2 and 37.6 %). Neutral sugar analysis showed that 61 the pectin extracted at pH 6.0 contained more neutral sugars, particularly, galactose 62 (21.7 -25.7 mol%), rhamnose (10.1 -13.2 mol%) and arabinose (7.1 -7.3 mol%) 63 than that extracted at pH 2.0 indicating variations in fine structure. In addition, 64 molecular parameters of the isolated pectins, such as intrinsic viscosity (2.8 -4.4 dL 65 g -1 ), critical concentration (0.15 -0.45 dL g -1 ) and coil overlap parameter (0.66 -66 1.51), showed that extraction conditions resulted in pectin with different chain 67 morphology. The yield and physico-chemical characteristics of the extracted pectin 68 from okra pods were influenced by the extraction conditions. 69 70 71

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“…; Sigma; X4252) and pectin from citrus (Citrus aurantium) fruit (Sigma; P9436). Apoplastic fluid (1.28 3 10 21 mg of total protein) was incubated with 20 mg of xylan or pectin in 1 mL of 0.1 M sodium phosphate buffer (pH 7.0) at 37°C for 24 h. At each time point, 100 mL of sample was boiled for 15 min at 100°C to terminate the reaction, dried, and used for acetyl amount determination according to the protocol of McComb and McCready (1957;see below).…”

Section: Assays For Acetyl Esterase Activitymentioning

confidence: 99%

Arabidopsis and Brachypodium distachyon Transgenic Plants Expressing Aspergillus nidulans Acetylesterases Have Decreased Degree of Polysaccharide Acetylation and Increased Resistance to Pathogens

et al. 2013

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The plant cell wall has many significant structural and physiological roles, but the contributions of the various components to these roles remain unclear. Modification of cell wall properties can affect key agronomic traits such as disease resistance and plant growth. The plant cell wall is composed of diverse polysaccharides often decorated with methyl, acetyl, and feruloyl groups linked to the sugar subunits. In this study, we examined the effect of perturbing cell wall acetylation by making transgenic Arabidopsis (Arabidopsis thaliana) and Brachypodium (Brachypodium distachyon) plants expressing hemicellulose-and pectin-specific fungal acetylesterases. All transgenic plants carried highly expressed active Aspergillus nidulans acetylesterases localized to the apoplast and had significant reduction of cell wall acetylation compared with wild-type plants. Partial deacetylation of polysaccharides caused compensatory up-regulation of three known acetyltransferases and increased polysaccharide accessibility to glycosyl hydrolases. Transgenic plants showed increased resistance to the fungal pathogens Botrytis cinerea and Bipolaris sorokiniana but not to the bacterial pathogens Pseudomonas syringae and Xanthomonas oryzae. These results demonstrate a role, in both monocot and dicot plants, of hemicellulose and pectin acetylation in plant defense against fungal pathogens.The cell wall is one of the most important compartments of the plant cell. This external cell skeleton plays an important role in cell and tissue shape determination. Besides its structural role, this extracellular complex is involved in the control of important functions such as cell-cell interactions, whole-plant growth, development, and interaction with the environment. The plant cell wall is mainly composed of highly dynamic heteropolysaccharides assembled in macromolecular Besides the diversity of monosaccharide composition, cell wall polysaccharides are also modified with methyl, acetyl, and feruloyl groups, which are mainly O-linked to sugars. These functional groups are believed to protect polysaccharides from the action of specific glycosyl hydrolases and to cross link cell wall constituents controlling cell extensibility (Perrone et al., 2002;Gou et al., 2012). For example, methylesterification/

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Determination of Acetyl in Pectin and in Acetylated Carbohydrate Polymers

Cited by 272 publications

References 19 publications

Dominance of sphingomonads in a copper-exposed biofilm community for groundwater treatment

Dominance of sphingomonads in a copper-exposed biofilm community for groundwater treatment

Isolation and characterization of acetylated LM-pectins extracted from okra pods

Arabidopsis and Brachypodium distachyon Transgenic Plants Expressing Aspergillus nidulans Acetylesterases Have Decreased Degree of Polysaccharide Acetylation and Increased Resistance to Pathogens

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