Okra pectin contains an unusual substitution of its rhamnosyl residues with acetyl and alpha-linked galactosyl groups

Sengkhamparn, Nipaporn; Bakx, Edwin J.; Verhoef, René; Schols, Henk A.; Sajjaanantakul, Tanaboon; Voragen, A.G.J.

doi:10.1016/j.carres.2008.11.022

Cited by 111 publications

(62 citation statements)

References 32 publications

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“…However, it is likely that acetyl groups are not distributed homogeneously along the pectic backbone but are clustered in particular regions of HG and RG-I, as suggested for sugar beet . Recently, acetylation of rhamnose residues of RG-I was observed in okra (Abelmoschus esculentus) pectin (Sengkhamparn et al 2009). It is becoming clear that the acetylation pattern of pectin is complex.…”

Section: Introductionmentioning

confidence: 99%

Expression of mung bean pectin acetyl esterase in potato tubers: effect on acetylation of cell wall polymers and tuber mechanical properties

Orfila

Degan

Jørgensen

et al. 2012

Planta

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A mung bean (Vigna radiata) pectin acetyl esterase (CAA67728) was heterologously expressed in tubers of potato (Solanum tuberosum) under the control of the granule-bound starch synthase promoter or the patatin promoter in order to probe the significance of O-acetylation on cell wall and tissue properties. The recombinant tubers showed no apparent macroscopic phenotype. The enzyme was recovered from transgenic tubers using a high ionic strength buffer and the extract was active against a range of pectic substrates. Partial in vivo de-acetylation of cell wall polysaccharides occurred in the transformants, as shown by a 39% decrease in the degree of acetylation (DA) of tuber cell wall material (CWM). Treatment of CWM using a combination of endo-polygalacturonase and pectin methyl esterase extracted more pectin polymers from the transformed tissue compared to wild type. The largest effect of the pectin acetyl esterase (68% decrease in DA) was seen in the residue from this extraction, suggesting that the enzyme is preferentially active on acetylated pectin that is tightly bound to the cell wall. The effects of acetylation on tuber mechanical properties were investigated by tests of failure under compression and by determination of viscoelastic relaxation spectra. These tests suggested that de-acetylation resulted in a stiffer tuber tissue and a stronger cell wall matrix, as a result of changes to a rapidly relaxing viscoelastic component. These results are discussed in relation to the role of pectin acetylation in primary cell walls and its implications for industrial uses of potato fibres.

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Section: Introductionmentioning

confidence: 99%

Expression of mung bean pectin acetyl esterase in potato tubers: effect on acetylation of cell wall polymers and tuber mechanical properties

Orfila

Degan

Jørgensen

et al. 2012

Planta

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“…The composition of the okra gum has been studied in-depth by several research groups and the major cell wall polysaccharides from okra pods were shown to be rich in galactose, rhamnose and galacturonic acid [27]. In addition, pectin was shown to contain an unusual substitution of its rhamnosyl residues with acetyl and alpha-linked galactosyl groups [28]. The major antioxidants in okra were determined to be quercetin 3-O-xylosyl (1''' → 2'') glucoside, quercetin 3-Oglucosyl (1''' → 6'') glucoside, quercetin 3-Oglucoside and quercetin 3-O-(6''-O-malonyl)-glucoside [29].…”

Section: Properties and Composition Of The A Esculentus Extractmentioning

confidence: 98%

Antibacterial properties of the extract of Abelmoschus esculentus

Carvalho

Cruz

Fonseca

et al. 2011

Biotechnol Bioproc E

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In this study, antimicrobial properties of both lyophilized and fresh water extracts of the okra pods were assessed against Rhodococcus erythropolis and R. opacus, Mycobacterium sp. and M. aurum, Staphylococcus aureus, Escherichia coli, and Xanthobacter Py2. The extracts were effective against all bacterial strains tested, except R. erythropolis and the fresh extract displayed better antimicrobial properties than the lyophilized extract. A fresh extract concentration of 97.7 mg/mL was sufficient to kill all S. aureus cells, which is a worldwide source of nosocomial infection. The extract was also effective in inhibiting the growth of both Mycobacterium strains, X. Py2 and S. aureus, but was ineffective against R. erythropolis and E. coli. The lipid fraction of the okra gum was found to be responsible for the antibacterial properties and the protein and polysaccharide fractions displayed no antimicrobial activity. The two major constituents of the lipid fraction, palmitic and stearic acids, were apparently responsible for the antimicrobial properties of the okra extract.

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“…Acetylation is commonly found in the backbone of mannans and xylans and in the side chains of xyloglucans (Scheller and Ulvskov, 2010). Acetylation of the GalUA residues of pectin is found in both homogalacturonan and rhamnogalacturonan I (RGI; Ishii, 1997;Mohnen, 2008), and acetylation of rhamnosyl residues of RGI has been reported (Sengkhamparn et al, 2009). Extraction and separation of cell wall polymers often involves alkaline treatment, which removes acetate esters.…”

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confidence: 99%

Loss-of-Function Mutation of REDUCED WALL ACETYLATION2 in Arabidopsis Leads to Reduced Cell Wall Acetylation and Increased Resistance to Botrytis cinerea

et al. 2011

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Nearly all polysaccharides in plant cell walls are O-acetylated, including the various pectic polysaccharides and the hemicelluloses xylan, mannan, and xyloglucan. However, the enzymes involved in the polysaccharide acetylation have not been identified. While the role of polysaccharide acetylation in vivo is unclear, it is known to reduce biofuel yield from lignocellulosic biomass by the inhibition of microorganisms used for fermentation. We have analyzed four Arabidopsis (Arabidopsis thaliana) homologs of the protein Cas1p known to be involved in polysaccharide O-acetylation in Cryptococcus neoformans. Loss-of-function mutants in one of the genes, designated REDUCED WALL ACETYLATION2 (RWA2), had decreased levels of acetylated cell wall polymers. Cell wall material isolated from mutant leaves and treated with alkali released about 20% lower amounts of acetic acid when compared with the wild type. The same level of acetate deficiency was found in several pectic polymers and in xyloglucan. Thus, the rwa2 mutations affect different polymers to the same extent. There were no obvious morphological or growth differences observed between the wild type and rwa2 mutants. However, both alleles of rwa2 displayed increased tolerance toward the necrotrophic fungal pathogen Botrytis cinerea.

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Okra pectin contains an unusual substitution of its rhamnosyl residues with acetyl and alpha-linked galactosyl groups

Cited by 111 publications

References 32 publications

Expression of mung bean pectin acetyl esterase in potato tubers: effect on acetylation of cell wall polymers and tuber mechanical properties

Expression of mung bean pectin acetyl esterase in potato tubers: effect on acetylation of cell wall polymers and tuber mechanical properties

Antibacterial properties of the extract of Abelmoschus esculentus

Loss-of-Function Mutation of REDUCED WALL ACETYLATION2 in Arabidopsis Leads to Reduced Cell Wall Acetylation and Increased Resistance to Botrytis cinerea

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