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BACKGROUND: Loquat peel, often as food waste, is a valuable source of bioactive polysaccharides. However, study of such polysaccharides is insufficient, leaving a significant gap in understanding their preparation, structure and bioactivities. RESULTS: In this study, three types of loquat peel polysaccharides (LPWP, LPHP and LPNP) were sequentially extracted using hot water, HCl and NaOH solutions, respectively. Among them, LPWP was the purest, with a yield of 3.4% and molecular weight of 470.6 kDa, and it differed from LPHP and LPNP in structure, as evidenced by Fourier transform infrared spectroscopy, X‐ray diffraction and scanning electron microscopy, which demonstrated that LPWP consisted of more arabinose (Ara) but less galacturonic acid, rhamnose and galactose, with molar percentages of 71.3%, 23.3%, 3.5% and 1.9%, respectively. Besides, LPWP also exhibited superior antioxidant and antihyperglycemic activities in vitro, particularly in inhibiting α‐amylase and α‐glucosidase. Methylation and nuclear magnetic resonance analysis confirmed that LPWP was a methyl‐esterified pectic polysaccharide rich in branched arabinan, as evidenced by the notable proportion of α‐Ara residues, including T‐α‐Araf, 1,5‐α‐Araf and 1,2,3,5‐α‐Araf, with molar percentages of 27.1%, 23.1% and 10.2%, respectively. AFM imaging further revealed its branched‐chain morphology and aggregation behavior. CONCLUSION: This study highlights the potential of loquat peel polysaccharides as a bioactive ingredient with significant antioxidant and antihyperglycemic properties, particularly LPWP, which was found as a methyl‐esterified pectic polysaccharide with abundant‐branched arabinan. Our work provides valuable insights into the application of loquat peel polysaccharides in functional foods. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Hempseed (Cannabis sativa L.) is a valuable source of oil and a quality vegetable protein source, but little is known about its fiber composition. This study provides the most extensive characterization of hempseed cell wall polysaccharides to date. Quantification of total dietary fiber (TDF) and acetyl bromide soluble lignin (ABSL), monosaccharide composition through two complimentary hydrolysis methods (Saeman hydrolysis and methanolysis), and linkage analysis via derivatization of monosaccharides to partially methylated alditol acetates (PMAAs) were done. More detailed profiling of hempseed xyloglucans and pectic arabinans and galactans was performed via targeted enzymatic generation and quantification of characteristic oligosaccharides. Hempseed's cell wall polysaccharide profile is consistent with the primary cell walls of dicots, but it is particularly abundant in linear xylans, presumably from secondary cell walls. The hempseed water-insoluble cell wall material was mostly composed of cellulose and xylans, but pectins (including arabinans with a low degree of branching and galactans), xyloglucans with L- and F-motifs and a relatively low substitution rate, and mannans were also present. These data show that hempseed is a good source of complex dietary fiber for human diets and a potential fiber additive for herbivorous livestock diets. Potential consequences of these carbohydrate structural details on hempseed's microbial fermentability are discussed. [ABSTRACT FROM AUTHOR]

Abstract Bifidobacterium adolescentis gene BAD_1527 has previously been suggested to code for a β-xylosidase (Kobayashi et al., Mar Drugs 18:174, 2020). Our detailed investigation of the substrate specificity of the GH43_22 protein using a wide spectrum of natural and artificial substrates showed that the enzyme hydrolyzed neither linear xylooligosaccharides nor glucuronoxylan. Xylose was released only from the artificial 4-nitrophenyl β-D-xylopyranoside (1.58 mU/mg). The corresponding α-L-arabinofuranoside was by three orders of magnitude better substrate (2.17 U/mg). Arabinose was the only monosaccharide liberated from arabinoxylan and α-1,3- or α-1,2-singly arabinosylated xylooligosaccharides. Moreover, the enzyme efficiently debranched sugar beet arabinan and singly arabinosylated α-1,5-L-arabinooligosaccharides, although short linear α-1,5-L-arabinooligosaccharides were also slowly degraded. On the other hand, debranched arabinan, arabinogalactan as well as 2,3-doubly arabinosylated main chain residues of arabinan and arabinoxylan did not serve as substrates. Thus, the enzyme encoded by the BAD_1527 gene is a typical α-L-arabinofuranosidase of AXH-m specificity.

The increasing number of uncharacterized proteins in the CAZy database highlights the importance of their functional characterization. Therefore, the substrate and positional specificity of 34 α-L-arabinofuranosidases classified into GH43, GH51, and GH62 families was determined on arabinoxylan, arabinan, and derived oligosaccharides (many enzyme–substrate combinations were examined for the first time) covering all possible kinds of arabinofuranosyl branches using TLC. Arabinoxylan was efficiently debranched by the majority of the tested proteins. Most of them showed AXH-m specificity, acting on 2- or 3-monoarabinosylated substrates, while AXH-d3 specificity (liberation of 3-linked arabinose solely from 2,3 doubly decorated substrates) was found mainly in the subfamily GH43_10, harbouring enzymes of both types. Several GH51 enzymes, however, released arabinose also from a xylooligosaccharide doubly arabinosylated at the non-reducing end. The AXH-m and AXH-d3 specificities correlated well with the dearabinosylation of arabinan and arabinooligosaccharides, which were debranched by all GH51 representatives and some GH43 and GH62 members. The GH51 and GH62 arabinan-debranching enzymes also hydrolyzed debranched arabinan, while within the GH43 family the linear arabinan-degrading ability was found only in the GH43_26 subfamily, comprising specific exo 1,5-α-L-arabinofuranosidases. This study demonstrates a first attempt in the systematic examination of a relationship between CAZy classification and substrate and positional specificities of various α-L-arabinofuranosidases. [ABSTRACT FROM AUTHOR]

Bifidobacterium adolescentis gene BAD_1527 has previously been suggested to code for a β-xylosidase (Kobayashi et al., Mar Drugs 18:174, 2020). Our detailed investigation of the substrate specificity of the GH43_22 protein using a wide spectrum of natural and artificial substrates showed that the enzyme hydrolyzed neither linear xylooligosaccharides nor glucuronoxylan. Xylose was released only from the artificial 4-nitrophenyl β-D-xylopyranoside (1.58 mU/mg). The corresponding α-L-arabinofuranoside was by three orders of magnitude better substrate (2.17 U/mg). Arabinose was the only monosaccharide liberated from arabinoxylan and α-1,3- or α-1,2-singly arabinosylated xylooligosaccharides. Moreover, the enzyme efficiently debranched sugar beet arabinan and singly arabinosylated α-1,5-L-arabinooligosaccharides, although short linear α-1,5-L-arabinooligosaccharides were also slowly degraded. On the other hand, debranched arabinan, arabinogalactan as well as 2,3-doubly arabinosylated main chain residues of arabinan and arabinoxylan did not serve as substrates. Thus, the enzyme encoded by the BAD_1527 gene is a typical α-L-arabinofuranosidase of AXH-m specificity. Key points: BAD_1527 gene encodes a protein releasing xylose from NPX, but not natural substrates L-Arabinose is released from natural substrates, similarly to other GH43_22 members The enzyme debranches arabinoxylan, branched arabinan and derived oligosaccharides [ABSTRACT FROM AUTHOR]

α-L-arabinofuranosidases can be produced by fungi, bacteria, and plants and are responsible for the cleavage of α-1,2, α-1,3, and α-1,5 glycosidic bonds in arabinose residues. Few recent studies have focused on the production of these enzymes by species of basidiomycetes. In the present study, we purified an α-L-arabinofuranosidase from the fungus Coriolopsis byrsina and evaluated its functional biochemical properties. The purified enzyme had an estimated molecular mass of 55 kDa with maximum activity at pH 3.5–4.5 and 50 °C, stability in the range of pH 3–8 at 4 °C for 24 h, and from 10 to 60 °C for 1 h. The enzyme was also stable in 5–10% ethanol after 24 h at 28 °C, retaining more than 60% activity. A negative effect on catalysis was noted for all evaluated ions, especially Fe3+ and Hg2+, retaining 25% and 33% activity, respectively, at 10 mmol L−1, and L-arabinose, with 50% activity at 0.2 mol L−1 and 30% at 0.9 mol L−1. The enzyme was active on p-nitrophenyl-α-L-arabinofuranoside (pNPA), p-nitrophenyl-β-D-xylopyranoside, linear 1,5 α-L-arabinan and xylan from beechwood. Kinetic assays under pNPA substrate indicated a KM of 3.45 ± 0.9 mmol L−1 and Vmax of 198.2 ± 24 μmol min−1 mg−1. These findings can serve as a reference for further tests of this enzyme aimed at improving the aroma of beverages and formulating enzyme cocktails for plant biomass degradation. [ABSTRACT FROM AUTHOR]

Gelation is a critical property of citrus pectin. However, the roles played by neutral sugar side-chains on acid-induced pectin gelation remain poorly understood. Herein, galactan- or/and arabinan-eliminated pectins (P-G, P-A, and P-AG) were used to investigate the effects of side-chains on gelation. The gel hardness values of citrus pectin, P-G, P-A, and P-AG were 42.6, 39.9, 5.3, and 2.1 g, respectively, suggesting that arabinan contributed more to gelation than galactan. We next found that arabinan branches promoted pectin chain entanglement more effectively than arabinan backbones. Destabilizer addition experiments showed that hydrogen bonding, electrostatic interaction, and hydrophobic interaction were the main forces affecting pectin gel networks and strength, which was further validated by molecular dynamic simulations. The total number of hydrogen bonds between the arabinan branches and galactan/HG (65.7) was significantly higher than that between the arabinan backbones and galactan/HG (39.1), indicating that arabinan branches predominated in terms of such interactions. This study thus elucidated the roles played by neutral-sugar side-chains, especially the arabinan branches of acid-induced pectin gels, in term of enhancing high-methoxyl pectin gelation, and offers novel insights into the structure-gelling relationships of citrus pectin. Arabinan branches greatly facilitate pectin aggregation by forming H-bonds and engaging in electrostatic and van der Waals interactions with HG and galactan, thus enhancing 3D network structure and gel strength. [Display omitted] [ABSTRACT FROM AUTHOR]

The role of sweet potato tubers in human nutrition is not new. The above-ground biomass of sweet potatoes is not used for nutritional purposes in most countries, but it has a high biological value. Therefore, the aim of the present study is to investigate the production of press fibre from above ground biomass by wet fractionation. Two sweet potato varieties (purple- and white-fleshed sweet potato) and two types of irrigation system were used: bubbling water flow system (BWS) and continuous water flow system (CWS). Glucan, xylan, arabinan were analysed by HPLC and elemental content was measured by ICP-OES. Our results show that the total carbohydrate content in the pressed fibre of the leaf blades (27.64-29.88% w/w) is lower than in the stem with petiole (51.14-57.36% w/w). No significant difference in glucan, xylan and arabinan content was observed in the leaf blade. In the stem with petiole, significant differences were observed for xylan and arabinan contents. For elemental content, generally higher values were measured in the leaf blade than in the stem with petiole. This information may be relevant for the selection of the appropriate variety and treatment, even for the production of functional food. [ABSTRACT FROM AUTHOR]

Glycoside hydrolase family 43 (GH43) represents a major source of arabinan- and arabinoxylan-active enzymes. Interestingly, some microbes remarkably enriched GH genes of this family, with the reason unknown. Hungateiclostridium clariflavum DSM 19,732 is an efficient lignocellulose degrader, which harbors up to 7 GH43 genes in its genome. We cloned three of the seven GH43 genes, and found that Abn43A is a unique endoarabinanase, which unprecedently showed approximately two times larger activity on sugar beet arabinan (116.8 U/mg) than that on linear arabinan, and it is efficient in arabinooligosaccharide production. Abn43B is an exoarabinanase which directly releases arabinose from linear arabinan. Abn43C is an α-L-arabinofuranosidase which is capable of splitting the arabinose side-chains from arabinooligosaccharides, arabinoxylooligosaccharides, and arabinoxylan. Most importantly, the three GH43 enzymes synergized in hydrolyzing arabinan. Compared to Abn43B alone, a supplement of Abn43A increased the arabinose production from linear arabinan by 150%, reaching 0.44 g/g arabinan. Moreover, an addition of Abn43C to Abn43A and Abn43B boosted the arabinose production from sugar beet arabinan by 15 times, reaching 0.262 g/g arabinan. Our work suggested the intensified functions of multiple GH43 enzymes toward arabinan degradation in H. clariflavum, and a potential synergetic mechanism among the three GH43 enzymes is suggested. Key points: • Endoarabinanase GH43A prefers branched substrate to linear one • Exoarabinanase GH43B can directly release arabinose from linear arabinan • The three GH43 enzymes synergized in arabinan hydrolysis [ABSTRACT FROM AUTHOR]

The above-ground part of the Salsola passerine was found to contain ~13% (w/w) of polysaccharides extractable with water and aqueous solutions of ammonium oxalate and sodium carbonate. The fractions extracted with aqueous sodium carbonate solutions had the highest yield. The polysaccharides of majority fractions are characterized by similar monosaccharide composition; namely, galacturonic acid and arabinose residues are the principal components of their carbohydrate chains. The present study focused on the determination of antioxidant activity of the extracted polysaccharide fractions and elucidation of the structure of polysaccharides using nuclear magnetic resonance (NMR) spectroscopy. Homogalacturonan (HG), consisting of 1,4-linked residues of α-D-galactopyranosyluronic acid (GalpA), rhamnogalacturonan-I (RG-I), which contains a diglycosyl repeating unit with a strictly alternating sequence of 1,4-linked D-GalpA and 1,2-linked L-rhamnopyranose (Rhap) residues in the backbone, and arabinan, were identified as the structural units of the obtained polysaccharides. HMBC spectra showed that arabinan consisted of alternating regions formed by 3,5-substituted and 1,5-linked arabinofuranose residues, but there was no alternation of these residues in the arabinan structure. Polysaccharide fractions scavenged the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical at 0.2–1.8 mg/mL. The correlation analysis showed that the DPPH scavenging activity of polysaccharide fractions was associated with the content of phenolic compounds (PCs). [ABSTRACT FROM AUTHOR]

Green biorefining uses fresh lignocellulosic biomass to produce green juice and pressed fibre fractions by wet fractionation. The latter is a byproduct, accounting for 25–32% of the starting material. In this study, the composition (glucan, xylan, arabinan, lignin, total phenol, flavonoid and protein) of pressed fibres obtained from four alfalfa, four soy and one broccoli varieties were determined at different harvest times. Statistical analyses were performed to determine the effects of harvest time and variety on the measured parameters. In most of the cases, there were interactions between the effects of harvest time and variety. Among alfalfa varieties, OLI1 had the highest carbohydrate (52.09 w/w%) and DIM3 had the lowest lignin (13.02 w/w%) content. In the case of soy, the ADV2 variety had the highest carbohydrate (53.47 w/w%) and PK1 had the lowest lignin (11.14 w/w%) content. Broccoli contained low amounts of carbohydrates (44.94 w/w%) and lignin (10.16 w/w%). The phenolic and flavonoid contents were similar for each species, but the protein content was the highest in alfalfa fibre. Based on these data, the most promising species, varieties and harvesting time can be selected in terms of a certain component that could be essential to produce functional foods with enhanced nutritional value. [ABSTRACT FROM AUTHOR]

Arabinan in plant cell wall constitutes a major source of arabinose and arabino-oligosaccharides in nature. Exo-α- l -1,5-arabinanases release arabinose or arabino-oligosaccharides from arabinan in an exo-acting manner and therefore contribute to arabinan degradation. In this study, an exo-α- l -1,5-arabinanase belonging to GH93 family was identified from the thermophilic filamentous fungus Rasamsonia emersonii. The corresponding encoding gene (Reabn93) was cloned from the R. emersonii genome and heterologously expressed in Pichia pastoris. The purified recombinant ReAbn93 exhibited the maximum activity at 70 °C and retained 70% of its activity after incubation at 70 °C for 3 h ReAbn93 had an acidic pH optimum (pH 4.0) but remained stable over a broad pH range (pH 3–9). The specific activity of ReAbn93 toward linear arabinan under optimal conditions was 466.08 U mg−1. Similar to the few other reported GH93 members, ReAbn93 degrades linear arabinan or arabino-oligosaccharides in an exo-acting manner with arabinobiose as the only hydrolytic product. Of note, ReAbn93 possessed remarkably better thermostability and higher specific activity compared to the only reported thermophilic counterpart in GH93, and therefore holds potential in relevant biotechnological applications. [ABSTRACT FROM AUTHOR]

An arabinan-rich acidic polysaccharide, named ALP4-2 ([ α ]20 D = +197.8 (c 1.0 mg/mL, H 2 O); and M w = 5.59 × 103 g/mol), was obtained from Atractylodes lancea (Thunb.) DC. ALP4-2 is mainly comprised of Ara along with a small amount of GalA, Gal, Rha, Glc and Xyl. The structure was decorated by glycosidic linkages of α -Ara f -(1→, →3)- α -Ara f -(1→, →5)- α -Ara f -(1→, →3,5)- α -Ara f -(1→, →2,4)- α -Rha p -(1→, α -GalA p -(1→, →4)- α -GalA p -6-OMe-(1→, →4)- α -GalA p -6-OMe and β -Gal p -(1→ with a ratio of 6:1:7:5:5:1:7:1:4. The structure, configuration and microstructure of ALP4-2 was proposed by comprehensive considerations of results from SEC-MALLS-RID, SEC-HRMS, GC–MS, and 1D/2D NMR spectroscopy. Except for a high methyl ester in full pectin regions, an abundant arabinan moiety is observed in ALP4-2 with highly complex and branched characteristics. The immunoactivity displayed that ALP4-2 can significantly promote phagocytosis of macrophage without cytotoxicity, and stimulate nitric oxide and cytokines (TNF- α , IL-6 and IL-10) release on RAW 264.7. • An arabinan-rich polysaccharide (ALP4-2) is obtained from Atractylodes lancea. • Structure of ALP4-2 is clarified by multiple MS techniques and 1D/2D NMR. • ALP4-2 shows potent immunomodulatory activities in vitro by stimulating RAW 264.7 cells. [ABSTRACT FROM AUTHOR]

The cell walls of forage chicory (Cichorium intybus) leaves are known to contain high proportions of pectic polysaccharides. However, little is known about the distribution of pectic polysaacharides among walls of different cell types/tissues and within walls. In this study, immunolabelling with four monoclonal antibodies was used to map the distribution of pectic polysaccharides in the cell walls of the laminae and midribs of these leaves. The antibodies JIM5 and JIM7 are specific for partially methyl-esterified homogalacturonans; LM5 and LM6 are specific for (1→4)-β-galactan and (1→5)-α-arabinan side chains, respectively, of rhamnogalacturonan I. All four antibodies labelled the walls of the epidermal cells with different intensities. JIM5 and JIM7, but not LM5 or LM6, labelled the middle lamella, tricellular junctions, and the corners of intercellular spaces of ground, xylem and phloem parenchyma. LM5, but not LM6, strongly labelled the walls of the few sclerenchyma fibres in the phloem of the midrib and lamina vascular bundles. The LM5 epitope was absent from some phloem parenchyma cells. LM6, but not LM5, strongly labelled the walls of the stomatal guard cells. The differential distribution of pectic epitopes among walls of different cell types and within walls may reflect the deposition and modification of these polysaccharides which are involved in cell wall properties and cell development.

The cell walls of forage chicory (Cichorium intybus) leaves are known to contain high proportions of pectic polysaccharides. However, little is known about the distribution of pectic polysaacharides among walls of different cell types/tissues and within walls. In this study, immunolabelling with four monoclonal antibodies was used to map the distribution of pectic polysaccharides in the cell walls of the laminae and midribs of these leaves. The antibodies JIM5 and JIM7 are specific for partially methyl-esterified homogalacturonans; LM5 and LM6 are specific for (1→4)-β-galactan and (1→5)-α-arabinan side chains, respectively, of rhamnogalacturonan I. All four antibodies labelled the walls of the epidermal cells with different intensities. JIM5 and JIM7, but not LM5 or LM6, labelled the middle lamella, tricellular junctions, and the corners of intercellular spaces of ground, xylem and phloem parenchyma. LM5, but not LM6, strongly labelled the walls of the few sclerenchyma fibres in the phloem of the midrib and lamina vascular bundles. The LM5 epitope was absent from some phloem parenchyma cells. LM6, but not LM5, strongly labelled the walls of the stomatal guard cells. The differential distribution of pectic epitopes among walls of different cell types and within walls may reflect the deposition and modification of these polysaccharides which are involved in cell wall properties and cell development. [ABSTRACT FROM AUTHOR]

Green biorefining uses fresh lignocellulosic biomass to produce green juice and pressed fibre fractions by wet fractionation. The latter is a byproduct, accounting for 25–32% of the starting material. In this study, the composition (glucan, xylan, arabinan, lignin, total phenol, flavonoid and protein) of pressed fibres obtained from four alfalfa, four soy and one broccoli varieties were determined at different harvest times. Statistical analyses were performed to determine the effects of harvest time and variety on the measured parameters. In most of the cases, there were interactions between the effects of harvest time and variety. Among alfalfa varieties, OLI1 had the highest carbohydrate (52.09 w/w%) and DIM3 had the lowest lignin (13.02 w/w%) content. In the case of soy, the ADV2 variety had the highest carbohydrate (53.47 w/w%) and PK1 had the lowest lignin (11.14 w/w%) content. Broccoli contained low amounts of carbohydrates (44.94 w/w%) and lignin (10.16 w/w%). The phenolic and flavonoid contents were similar for each species, but the protein content was the highest in alfalfa fibre. Based on these data, the most promising species, varieties and harvesting time can be selected in terms of a certain component that could be essential to produce functional foods with enhanced nutritional value.

Extracellular glycosyl hydrolases are uncommon in lactobacilli and include amylases and fructosidases mediating starch and fructan utilization, respectively. Extracellular arabinanases have not been described in lactobacilli. This study is aimed at identifying the function of an arabinan utilization operon in Lactobacillus crispatus DSM29598 and at characterizing two putative extracellular arabinanases that are located on that operon. The arabinan utilization operon of L. crispatus DSM29598 encodes enzymes for degradation of arabinan, α-galactosidases, β-galactosidases, and enzymes and for utilization of arabinose including phosphoketolase. The two putative extracellular arabinanases, AbnA and AbnB, are homologous to family GH43 endo-arabinanases. In Lactobacillaceae, homologs of these enzymes were identified exclusively in vertebrate-adapted species of the genus Lactobacillus. L. crispatus grew with arabinan from sugar beet pectin as sole carbon source, indicating extracellular arabinanase activity, and produced lactate and acetate, indicating metabolism via the phosphoketolase pathway. The two arabinanases AbnA and AbnB were heterologously expressed and purified by affinity chromatography. AbnA hydrolyzed linear and branched arabinan, while AbnB hydrolyzed only linear arabinan. The optimum pH for AbnA and AbnB was 6 and 7.5, respectively; 40 °C was the optimum temperature for both enzymes. The application of arabinan degrading L. crispatus as probiotic or as synbiotic with pectins may improve the production of short-chain fatty acids from pectin to benefit host health. Key points: • An arabinan utilization operon in L. crispatus encodes two extracellular arabinanases. • The same operon also encodes metabolic genes for arabinose conversion. • In Lactobacillaceae, extracellular arabinanases are exclusive to Lactobacillus species. [ABSTRACT FROM AUTHOR]

Arabinanases from glycoside hydrolase family GH93 are enzymes with exo-activity that hydrolyze the α-1,5 bonds between arabinose residues present on arabinan. Currently, several initiatives aiming to use byproducts rich in arabinan such as pectin and sugar beet pulp as raw material to produce various compounds of interest are being developed. However, it is necessary to use robust enzymes that have an optimal performance under pH and temperature conditions used in the industrial processes. In this work, the first GH93 from the thermophilic fungus Thermothielavioides terrestris (Abn93T) was heterologously expressed in Aspergillus nidulans, purified and biochemically characterized. The enzyme is a thermophilic glycoprotein (optimum activity at 70 °C) with prolonged stability in acid pHs (4.0 to 6.5). The presence of glycosylation affected slightly the hydrolytic capacity of the enzyme, which was further increased by 34% in the presence of 1 mM CoCl2. Small-angle X-ray scattering results show that Abn93T is a globular-like-shaped protein with a slight bulge at one end. The hydrolytic mechanism of the enzyme was elucidated using capillary zone electrophoresis and molecular docking calculations. Abn93T has an ability to produce (in synergism with arabinofuranosidases) arabinose and arabinobiose from sugar beet arabinan, which can be explored as fermentable sugars and prebiotics. Key points: • Thermophilic exo-arabinanase from family GH93 • Molecular basis of arabinan depolymerization [ABSTRACT FROM AUTHOR]

In apple (Malus × domestica) fruit, the different layers of the exocarp (cuticle, epidermis, and hypodermis) protect and maintain fruit integrity, and resist the turgor-driven expansion of the underlying thin-walled cortical cells during growth. Using in situ immunolocalization and size exclusion epitope detection chromatography, distinct cell type differences in cell wall composition in the exocarp were revealed during apple fruit development. Epidermal cell walls lacked pectic (1→4)-β- d -galactan (associated with rigidity), whereas linear (1→5)-α- l -arabinan (associated with flexibility) was exclusively present in the epidermal cell walls in expanding fruit and then appeared in all cell types during ripening. Branched (1→5)-α- l -arabinan was uniformly distributed between cell types. Laser capture microdissection and RNA sequencing (RNA-seq) were used to explore transcriptomic differences controlling cell type-specific wall modification. The RNA-seq data indicate that the control of cell wall composition is achieved through cell-specific gene expression of hydrolases. In epidermal cells, this results in the degradation of galactan side chains by possibly five β-galactosidases (BGAL2, BGAL7, BGAL10, BGAL11, and BGAL103) and debranching of arabinans by α-arabinofuranosidases AF1 and AF2. Together, these results demonstrate that flexibility and rigidity of the different cell layers in apple fruit during development and ripening are determined, at least in part, by the control of cell wall pectin remodelling. [ABSTRACT FROM AUTHOR]

Although there is considerable information on the chemistry of gelatinous (G) layers in tension wood (TW) fibers consisting of S1 + S2 + G cell wall structure (poplar), little is known on the chemistry of G-layers in TW fibers organized with S1+ G structure. This study investigated the distribution of lignin and non-cellulosic polysaccharides in ash TW fibers (S1+ G) using histochemistry and immunolocalization methods. TW fibers studied were fully developed (mature fibers) and obtained from two (TW-1, TW-2) mature European ash trees (Fraxinus excelsior L.). Based on differences in microfibril angle (MFA) and TW trees used, TW fibers were mainly classified into three types; 1) Type-1 fibers with MFA almost parallel to the fiber axis that were found in TW-1, 2) Type-2 fibers with 12° MFA that were abundant at the end of growth rings of TW-1 and 3) Type-3 fibers with 10° MFA that were found in TW-2. The S3 layer was absent in all TW fibers. In this study, the secondary cell wall structure of Type-1 and Type-2/Type-3 fibers were defined as G and GL (gelatinous-like) layers, respectively. Lignin with syringyl (S) units was detected in G/GL-layers, in which intensity and patterns of lignin staining likely related to the difference in MFA between G- and GL-layers. With hemicelluloses, heteroxylan and heteromannan epitopes were detected in G/GL-layers but these were much less abundant than those in S2 layers of normal wood (NW) fibers. Like lignin, distribution patterns of heteromannan epitopes in G/GL-layers likely related to differences in MFA between fiber types. Sparse xyloglucan epitopes were also detected in G/GL-layers. Homogalacturonan epitopes were absent in G/GL-layers. All fiber types showed abundant a -1, 5-arabinan epitopes in G/GL-layers. Overall results indicate that the chemistry of ash TW fibers studied differs significantly from that of other species reported previously, specifically TW fibers composed of S1 + S2 + G structure. [ABSTRACT FROM AUTHOR]

Guavira is a plant that belongs to Myrtaceae family, being widespread in the Brazilian Cerrado. In this study, pectic and hemicellulosic polysaccharides from guavira pomace, an agroindustry residue from pulp production, were structurally characterized using GPC, monosaccharide composition, methylation and NMR experiments. The absolute configurations of monosaccharides and the nature of uronic acids were attributed according to numerous data on the composition of related plant arabinogalactans and hemicelluloses present in the literature. An arabinan was purified, presenting Ara (85.0%), Rha (3.3%), Gal (7.7%) and GalA (4.0%). Mono and bidimensional NMR analyses of this arabinan demonstrated the presence of terminal β-L-Ara f units, whose occurrence has been scarcely reported in the literature. Hemicellulosic fraction contained a glucuronoxylan, with α-D-Glc p A/4- O -methyl-α-D-Glc p A group linked to O -2 of a (1 → 4)-β-D-xylan, presenting one uronic acid residue for every six xylose units. These findings about guavira pomace polysaccharides could contribute to develop future nutraceutical and technological uses for this industrial waste. Image 1 • Guavira pomace is an agroindustry residue from pulp production. • Pectic and hemicellulosic polysaccharides were structurally characterized. • Unusual pectin, a β-L-Ara f -containing arabinan was purified. • Hemicellulosic fraction contained a glucuronoxylan. [ABSTRACT FROM AUTHOR]

The objective of the study was to determine the changes brought about by malting/germination on the pectic polysaccharides (PP's), the major components of soluble fibres present in chickpea (Cicer arietinum L.) hull. Chickpea hull PP's were extracted sequentially using ammonium oxalate (AO) and ethylenediaminetetraacetic acid (EDTA), and a comparative study was conducted in native (unprocessed, N–PP) and after subjecting to 48 h malting process (M–PP). Malting process did not show a significant change in the respective yields of AO and EDTA extracted pectic polysaccharides. The degree of esterification of N–PP–EDTA through Fourier transform infrared spectroscopy was found to be five times (~ 21%) more than N–PP–AO (~ 4%). AO isolated PP's have more complexed xylogalacturonan with relatively more galactan side chains compared to EDTA isolated PPs. Proton (1H) nuclear magnetic resonance result further suggested the occurrence of arabinan rich rhamnogalacturonan in chickpea hull and malting process showed no significant changes in structure. [ABSTRACT FROM AUTHOR]

Abstract The polysaccharide PG W was isolated from peels and membranes of fruits of pomegranate P. granatum by hot water extraction. The methods of ion exchange chromatography, partial acid hydrolysis, enzymatic hydrolysis and NMR spectroscopy were employed to establish the major elements of its structure. It was shown that this polysaccharide contained polymers with different structures, the main components among which were pectic polysaccharides, represented mainly by highly methyl-esterified and lowly acetylated 1,4-α- d -galactopyranosyluronan and a minor amount of partially 2- O - and/or 3- O -acetylated RG-I. The side carbohydrate chains of the branched region of RG-I were mainly represented by terminal, 5- O -, 3- O -, 2,5-di- O -, 3,5-di- O - and 2,3,5-tri- O -substituted α- l -Ara f residues indicating the presence of branched 1,5-α- l -arabinan and minor regions of 1,4-β- d -galactan or arabinogalactan type I. The degree of methylation of the isolated pectins varied depending on the method of treatment. As a result, peels and membranes of pomegranate fruits can be recommended as a source of highly and lowly methyl-esterified pectic polysaccharides. Highlights • Structure of pomegranate peel pectin was characterized for the first time. • Homogalacturonic regions prevailed in pomegranate pectins. • RG-I side chains are formed of branched 1,5-α- l -arabinan and 1,4-β- d -galactan. • The isolated pectic polysaccharides were mainly by highly methyl-esterified. [ABSTRACT FROM AUTHOR]

Abstract: Chickpea (Cicer arietinum L.) is an important nutritionally rich legume crop that is consumed worldwide. Prior to cooking, desi chickpea seeds are most often dehulled and cleaved to release the split cotyledons, referred to as dhal. Compositional variation between desi genotypes has a significant impact on nutritional quality and downstream processing, and this has been investigated mainly in terms of starch and protein content. Studies in pulses such as bean and lupin have also implicated cell wall polysaccharides in cooking time variation, but the underlying relationship between desi chickpea cotyledon composition and cooking performance remains unclear. Here, we utilized a variety of chemical and immunohistological assays to examine details of polysaccharide composition, structure, abundance, and location within the desi chickpea cotyledon. Pectic polysaccharides were the most abundant cell wall components, and differences in monosaccharide and glycosidic linkage content suggest both environmental and genetic factors contribute to cotyledon composition. Genotype‐specific differences were identified in arabinan structure, pectin methylesterification, and calcium‐mediated pectin dimerization. These differences were replicated in distinct field sites and suggest a potentially important role for cell wall polysaccharides and their underlying regulatory machinery in the control of cooking time in chickpea. [ABSTRACT FROM AUTHOR]

A novel exo-arabinase (GH93, exo-ABN) enzyme produced by the ascomycete Penicillium canescens has been studied. Cloning of the abn1 gene coding for exo-ABN into the recipient P. canescens strain RN3-11-7 yielded recombinant producing strains characterized by a high yield of extracellular exo- ABN production (20-30% of the total amount of extracellular protein). Chromatographic purification yielded a homogenous exo-ABN with a molecular weight of 47 kDa, as shown by SDS-PAGE. The enzyme showed high specific activity towards linear arabinan (117 U/mg) and low specific activity towards branched arabinan and arabinoxylan (4-5 U/mg) and para-nitrophenyl-α-L-arabinofuranoside (0.3 U/mg), whereas arabinogalactan and para-nitrophenyl-α-L-arabinopyranoside, the substrates that contained the pyranose form of arabinose, were not hydrolyzed. Arabinohexaose was the major product of linear arabinan hydrolysis. Exo-ABN had a pH optimum at 5.0 and a temperature optimum at 60°C. The enzyme was stable in a broad pH range (4.0-7.0) and upon heating to 50°C during 180 min. Extensive hydrolysis of linear and branched arabinans by exo- and endo-arabinase mixtures, arabinofuranosidase, and arabinofuran-arabinoxylan hydrolase has been performed. The degree of substrate conversion amounted to 67 and 83% of the maximal possible value, respectively. [ABSTRACT FROM AUTHOR]

The endo-1,5-α-L-arabinanases (ABNases) belong to the glycoside hydrolase family 43 (GH43) and hydrolyse α-1,5-arabinofuranosidic bonds in arabinose-containing polysaccharides by an inverting mechanism. ABNases are key enzymes involved in hemicellulose degradation with various applications in food technology, organic synthesis and biofuel production. Here, the reaction mechanism of the Geobacillus stearothermophilus GH43 ABNases has been investigated using density functional theory method. To probe the role of the pKa modulators (Ser164 and Tyr229) in the reaction, two different orientations of a catalytic acid (Glu201) with respect to the position of these residues are considered. The results show that the orientation involving a hydrogen bond network (Ser164•••Glu201•••Tyr229) is energetically more favourable, compared to the other one (Ser164•••Glu201), with a barrier of 13.6 kcal mol−1, consistent with the experimental data. Our calculations also give support to a single displacement mechanism proposed in the literature where the protonation of glycosidic bond and a nucleophilic attack by a catalytic water occur in a concerted but asynchronous manner. [ABSTRACT FROM AUTHOR]

Plant–parasitic cyst nematodes induce the formation of specialized feeding structures, syncytia, within their host roots. These unique plant organs serve as the sole nutrient resource for development and reproduction throughout the biotrophic interaction. The multinucleate syncytium, which arises through local dissolution of cell walls and protoplast fusion of multiple adjacent cells, has dense cytoplasm containing numerous organelles, surrounded by thickened outer cell walls that must withstand high turgor pressure. However, little is known about how the constituents of the syncytial cell wall and their conformation support its role during nematode parasitism. We used a set of monoclonal antibodies, targeted to a range of plant cell wall components, to reveal the microstructures of syncytial cell walls induced by four of the most economically important cyst nematode species, Globodera pallida, Heterodera glycines, Heterodera avenae and Heterodera filipjevi, in their respective potato, soybean, and spring wheat host roots. In situ fluorescence analysis revealed highly similar cell wall composition of syncytia induced by G. pallida and H. glycines. Both consisted of abundant xyloglucan, methyl-esterified homogalacturonan and pectic arabinan. In contrast, the walls of syncytia induced in wheat roots by H. avenae and H. filipjevi contain little xyloglucan but are rich in feruloylated xylan and arabinan residues, with variable levels of mixed-linkage glucan. The overall chemical composition of syncytial cell walls reflected the general features of root cell walls of the different host plants. We relate specific components of syncytial cell walls, such as abundant arabinan, methyl-esterification status of pectic homogalacturonan and feruloylation of xylan, to their potential roles in forming a network to support both the strength and flexibility required for syncytium function.

The sorption capacity of arabinan-rich pectic polysaccharide (ARPP) onto ferulic acid (FA) was investigated using equilibrium dialysis assays. UV and FT-IR spectra showed that FA was successfully adsorbed by ARPP. The effects of temperature, pH, buffer concentration, NaCl, and ethanol on sorption were investigated. Sorption variable optimization was examined by response surface methodology. The order of influence of each factor in affecting the sorption capacity was temperature > pH > buffer concentration. The maximum sorption yield was 363.92 ± 18.37 μg/mg at 36.8 °C, pH 5.26, and a buffer concentration of 0.09 M. Langmuir, Freundlich, and Temkin models were used to fit the experimental data under the optimized conditions. The Freundlich model showed the closest fit with an R 2 of 0.995 and a △ q % of 6.44. Scatchard plots of FA binding to ARPP indicated the existence of two types of binding sites, Type-1 and Type-2 , which followed the Freundlich model. Significant decreases in the sorption of FA at elevated NaCl and ethanol concentrations indicated that hydrogen bonding and electrostatic forces involved in the sorption of FA onto ARPP. [ABSTRACT FROM AUTHOR]

Considering that natural polysaccharides are potential anti-inflammatory agents, in this study, an arabinan (RGP70–2) was isolated and purified from Rehmannia glutinosa Libosch. (R. glutinosa) and its structure was characterized. RGP70–2 was a homogeneous polysaccharide with a molecular weight of 6.7 kDa, with the main backbone comprising →5)- α -L-Ara f -(1→, →3)- α -L-Ara f -(1→, →2,3,5)- α -L-Ara f -(1→, and →2,5)- α -L-Ara f -(1 → linkages and the side chain comprising an α -L-Ara f -(1 → linkage. In vivo experiments showed that RGP70–2 inhibited ROS production and downregulated the expression of pro-inflammatory cytokines (TNF- α, IL-1 β , and IL-6). In vitro experiments showed that RGP70–2 decreased levels of pro-inflammatory cytokines, inhibited ROS production, and attenuated NF- κ B-p65 translocation from the cytoplasm to the nucleus. Our results showed that RGP70–2 may delay inflammation by regulating the ROS-NF- κ B pathway. Thus, RGP70–2 has potential applications as an anti-inflammatory agent in the biopharmaceutical industry. [Display omitted] [ABSTRACT FROM AUTHOR]

A comparative study of mucilage (locular tissue) and pulp polysaccharides from ripe tamarillo fruits ( Solanum betaceum Cav.) was carried out. After aqueous and alkaline extractions and various purification steps (freeze–thaw and α-amylase - EC 3.2.1.1 treatments, Fehling precipitation and ultrafiltration through 50 kDa cut-off membrane), the obtained fractions from mucilage were analyzed by sugar composition, HPSEC, and NMR spectroscopy analyses. The results showed that the mucilage of tamarillo contains a highly methoxylated homogalacturonans mixed with type I arabinogalactans, a linear (1 → 5)-linked α-L-arabinan, and a linear (1 → 4)-β-D-xylan. A comparison with polysaccharides extracted from the pulp revealed that differences were observed in the yield and in the ratio of extracted polysaccharides. Moreover, structural differences between pulp and mucilage polysaccharides were also observed, such as in the length of side chains of the pectins, and in the degree of branching of the xylans. [ABSTRACT FROM AUTHOR]

Despite the many health benefits of wild blackthorn fruits, their use is negligible and little explored. Preliminary results suggest that this fruit is a rich source of natural antioxidants. Antioxidant active fraction, extracted from wild blackthorn fruits by cold water extraction (Cw), was subjected to ion-exchange chromatography, which gave ten fractions after a successive elution with water, sodium chloride and sodium hydroxide solutions. Fraction eluted by water contained an arabinan of a low molecular weight (M w = 5000). Its chemical and spectroscopic studies have revealed a highly branched structure with backbone composed of 1,5-linked α- l -arabinofuranose residues; about 76% of them are branched dominantly through O3 and much less through O2, however, some arabinose units (∼8%) were fully branched. In addition to terminal α-L-Ara f , the presence of β-L-Ara f unit was also identified in blackthorn L-arabinan. Antioxidant activity tests of Cw ion exchange fractions revealed significant effects only of fractions eluted with 1 M sodium chloride (6F) and sodium hydroxide (7F) solutions, while phenolic free arabinan did not possess this effect. Phenolic compounds linked via α- l -arabinosyl side chains appear to be responsible for the antioxidant effect of two Cw fractions. [Display omitted] • Aqueous extraction of P. spinosa fruits yielded a phenolic polysaccharide-protein. • Its ion-exchange chromatography gave ten fractions. • The non-retained fraction gave crude L-arabinan. • The retained fractions were arabinogalactans, pectic and hemicellulose biopolymers. • The hemicellulose fraction showed the best antioxidant activity of all fractions. [ABSTRACT FROM AUTHOR]

Araucaria angustifolia is one of the main conifer species with great economic importance. Its seeds, known as pinhão , play a fundamental role in ecosystem conservation and have promising potential for application in the food/nutraceutical industry. This study aimed to elucidate the fine chemical structure of polysaccharides, showing for the first time the composition of non-starch polysaccharides present in the pinhão seeds. For this, the seeds were submitted to sequential extractions giving rise to the water polysaccharide (PW), and alkaline polysaccharides (PA2M), and (PA4M) fractions, obtained after aqueous, 2 mol L-1 and 4 mol L-1 NaOH extraction, respectively. The polysaccharides isolated showed the presence of glucose (between 96.8% and 76.3%) indicating starch as the main component of all fractions. Moreover, after enzymatic treatment, the PA4M-A fraction was obtained showing mostly arabinose in its monosaccharide composition. In this way, the chemical structure of PA4M-A was investigated by 1D 1H, 13C NMR and 2D 1H–13C HSQC, 1H–1H COSY and 1H–13C HMBC NMR spectroscopy, which demonstrated the presence of arabinans composed with a backbone of (1→5)-linked-α- L -arabinofuranosyl units substituted in O -2 and/or O -3 position by α- L -Ara f- (1→ or α- L -Ara f- (1→3)-α- L -Ara f- (1→ side chains. The structural elucidation of the arabinans presents in the pinhão cell wall contributes to the knowledge of the molecular structure of the A.angustifolia seeds. • Pinhão seeds non-starch polysaccharides are obtained by alkaline extraction. • After enzymatic treatment, the fraction PA4M-A shows mainly arabinose. • Fine structure of an arabinan from pinhão seeds is established for the first time. • PA4M-A comprise a backbone of (1→5)-linked-α- L -arabinofuranosyl units. • Branches in O -2 and/or O -3 position of arabinan are demonstrated by 2D NMR. [ABSTRACT FROM AUTHOR]

To date, the genus Mangrovimonas consists of only one species, Mangrovimonas yunxiaonensis strain LY01 that is known to have algicidal effects against harmful algal blooms (HABs) of Alexandrium tamarense . In this study, the whole genome sequence of three Mangrovimonas -like strains, TPBH4 T (= LMG 28913 T ,=JCM 30882 T ), ST2L12 T (= LMG 28914 T ,=JCM 30880 T ) and ST2L15 T (= LMG 28915 T ,=JCM 30881 T ) isolated from estuarine mangrove sediments in Perak, Malaysia were described. The sequenced genomes had a range of assembly size ranging from 3.56 Mb to 4.15 Mb which are significantly larger than that of M. yunxiaonensis LY01 (2.67 Mb). Xylan, xylose, L-arabinan and L-arabinose utilization genes were found in the genome sequences of the three Mangrovimonas -like strains described in this study. In contrast, these carbohydrate metabolism genes were not found in the genome sequence of LY01. In addition, TPBH4 T and ST2L12 T show capability to degrade xylan using qualitative plate assay method. [ABSTRACT FROM AUTHOR]

A short, robust, and expedient synthesis of various aryl α- l-arabinofuranosides using a trichloroacetimidate precursor is described. The procedure is compatible with a range of phenols with varying p Ka values and may be amenable for preparing a wide range of other glycosides. [ABSTRACT FROM AUTHOR]

Geobacillus sp. Y412MC52 was isolated from Obsidian Hot Spring, Yellowstone National Park, Montana, USA under permit from the National Park Service. The genome was sequenced, assembled, and annotated by the DOE Joint Genome Institute and deposited at the NCBI in December 2011 (CP002835). Based on 16S rRNA genes and average nucleotide identity, Geobacillus sp. Y412MC52 and the related Geobacillus sp. Y412MC61 appear to be members of a new species of Geobacillus. The genome of Geobacillus sp. Y412MC52 consists of one circular chromosome of 3,628,883 bp, an average G + C content of 52 % and one circular plasmid of 45,057 bp and an average G + C content of 45 %. Y412MC52 possesses arabinan, arabinoglucuronoxylan, and aromatic acid degradation clusters for degradation of hemicellulose from biomass. Transport and utilization clusters are also present for other carbohydrates including starch, cellobiose, and α- and β-galactooligosaccharides. [ABSTRACT FROM AUTHOR]

Arabinans and galactans are major components of the side-chains of pectin in plant cell walls. In order to understand how pectin side-chains interact with cellulose, in this work we studied the interaction of de-branched arabinan (from sugar beet) and linear galactan (from potato) during the synthesis of cellulose by Gluconacetobacter xylinus (ATCC 53524) to mimic in muro assembly. The binding studies reveal that arabinan and galactan are able to bind extensively (>200 mg/g of cellulose) during cellulose deposition, and more than pectin (from apple) in the absence of calcium. 13 C NMR revealed that associated arabinan, galactan or apple pectin molecules were neither rigid nor affected cellulose crystallinity, and there was no apparent change in cellulose architecture as reflected in scanning electron micrographs. De-binding of arabinan, galactan or apple pectin occurred as a result of washing, indicating a reversible binding to cellulose, which was modelled in terms of a surface-controlled process. Implications for structural models of primary plant cell walls and possible roles for cellulose binding of arabinan- and galactan-rich pectins in biological processes are discussed. [ABSTRACT FROM AUTHOR]

Objectives: The use of endo-arabinanase from Bacillus licheniformis (ABNase) for sugarcane saccharification has been evaluated by enzyme immobilization and commercial cocktail supplement with the immobilized heterologous protein. Results: Biochemical characterization of the purified ABNase showed that the catalytic activity was strongly inhibited by 5 mM Cu, Zn or Fe. The optimum pH and temperature for activity were 5.5-6.5 and 35-40 °C, respectively. The enzyme stability increased 128-fold when immobilized with glyoxyl agarose, and the hydrolysis of pretreated sugar cane biomass increased by 15 % when a commercial enzyme cocktail was supplemented with immobilized ABNase. Conclusion: Pectin hydrolysis by recombinant ABNase plays a role in the effective application of enzymatic cocktails for biomass saccharification. [ABSTRACT FROM AUTHOR]

Primary cell wall polysaccharides from aqueous extract of buriti fruit pulp ( Mauritia flexuosa , an exotic tropical palm) were isolated and characterized. After freeze–thaw and α-amylase treatments, extracted polysaccharides were purified by sequential ultrafiltration through membranes. Two homogeneous fractions were obtained, SBW-100R and SBW-30R (Mw of 126 kDa and 20 kDa, respectively). Monosaccharide composition, methylation and 13 C NMR analysis showed that fraction SBW-100R contained a (1 → 5)-linked arabinan, branched at O -3 and O -2 positions, linked to a type I rhamnogalacturonan. Low amounts of these polymers were also present in fraction SBW-30R according to 13 C NMR analysis and monosaccharide composition. However, a high methyl esterified homogalacturonan (HG) was present in higher proportions. These results reinforce previous findings present in literature data which indicate that pectic polysaccharides are found in high amounts in primary cell walls of palms, which are commelinid monocotyledons. [ABSTRACT FROM AUTHOR]

A structural characterization of polysaccharides obtained from edible tropical fruit named starfruit ( Averrhoa carambola L.) was carried out. After fractionation by freeze–thaw and Fehling precipitation, a pectic polysaccharide was obtained. It was composed of rhamnose, arabinose, galactose and uronic acid in the 5.0:72.5:12.1:10.4 molar ratios, respectively. A combination of monosaccharide, GPC, methylation and NMR analysis and enzymatic hydrolysis with endo-β-(1 → 4)-D-galactanase showed the presence of a rhamnogalacturonan I to which a branched arabinan and a type I arabinogalactan are attached. The arabinan moiety was formed by (1 → 5)-linked α-L-Ara f units in the backbone, branched only at O -3 by (1 → 2)- and (1 → 3)-linked α-L-Ara f units, while the type I arabinogalactan was formed by (1 → 4)- and (1 → 4,6)-linked β-D-Gal p units in the backbone with (1 → 5)-, (1 → 3,5)- and (1 → 3)-linked α-L-Ara f units as side chains. [ABSTRACT FROM AUTHOR]

Plant arabinan has important biological activity. In this study, a water-soluble arabinan ( M w ∼ 6.15 kDa) isolated from the stems of Ephedra sinica was found to consist of (1→5)-Araƒ, (1→3,5)-Araƒ, T-Araƒ, (1→3)-Araƒ and (1→2,5)-Araƒ residues at proportions of 10:2:3:2:1. A tentative structure was proposed by methylation analysis, nuclear magnetic resonance (NMR) spectroscopy ( 1 H NMR, 13 C NMR, DEPT-135, 1 H– 1 H COSY, HSQC, HMBC and ROESY) and literature. The structure proposed includes a branched (1→5)- α -Ara f backbone where branching occurs at the O-2 and O-3 positions of the residues with 7.7% and 15.4% of the 1,5-linked α -Ara f substituted at the O-2 and O-3 positions. The presence of a branched structure was further observed by atomic force microscopy. This polymer was characterized as having a much longer linear (1→5)- α -Ara f backbone as a repeating unit. In particular, the presence of α -Ara f →3)- α -Ara f -(1→3)- α -Ara f -(1→ attached at the O-2 is a new finding. This study may facilitate a deeper understanding of structure–activity relationships of biological polysaccharides from the stems of E. sinica . [ABSTRACT FROM AUTHOR]

Substantial differences in softening behaviour can exist between fruit even within the same species. Apple cultivars ‘Royal Gala’ and ‘Scifresh’ soften at different rates despite having a similar genetic background and producing similar amounts of ethylene during ripening. An examination of cell wall metabolism from the fruitlet to the ripe stages showed that in both cultivars pectin solubilisation increased during cell expansion, declined at the mature stage and then increased again during ripening. This process was much less pronounced in the slower softening ‘Scifresh’ than in ‘Royal Gala’ at every developmental stage examined, consistent with less cell separation and softening in this cultivar. Both cultivars also exhibited a progressive loss of pectic galactan and arabinan side chains during development. The cell wall content of arabinose residues was similar in both cultivars, but the galactose residue content in ‘Scifresh’ remained higher than that of ‘Royal Gala’ at every developmental stage. The higher content of cell wall galactose residue in ‘Scifresh’ cell walls correlated with a lower β-galactosidase activity and more intense immunolabelling of RG-I galactan side chains in both microscopy sections and glycan microarrays. A high cell wall galactan content has been associated with reduced cell wall porosity, which may restrict access of cell wall-modifying enzymes and thus maintain better structural integrity later in development. The data suggest that the composition and structure of the cell wall at very early development stages may influence subsequent cell wall loosening, and may even predispose the wall's ensuing properties. [ABSTRACT FROM AUTHOR]

Background: While it is kno3wn that complex tissues with specialized functions emerged during land plant evolution, it is not clear how cell wall polymers and their structural variants are associated with specific tissues or cell types. Moreover, due to the economic importance of many flowering plants, ferns have been largely neglected in cell wall comparative studies. Results: To explore fern cell wall diversity sets of monoclonal antibodies directed to matrix glycans of angiosperm cell walls have been used in glycan microarray and in situ analyses with 76 fern species and four species of lycophytes. All major matrix glycans were present as indicated by epitope detection with some variations in abundance. Pectic HG epitopes were of low abundance in lycophytes and the CCRC-M1 fucosylated xyloglucan epitope was largely absent from the Aspleniaceae. The LM15 XXXG epitope was detected widely across the ferns and specifically associated with phloem cell walls and similarly the LM11 xylan epitope was associated with xylem cell walls. The LM5 galactan and LM6 arabinan epitopes, linked to pectic supramolecules in angiosperms, were associated with vascular structures with only limited detection in ground tissues. Mannan epitopes were found to be associated with the development of mechanical tissues. We provided the first evidence for the presence of MLG in leptosporangiate ferns. Conclusions: The data sets indicate that cell wall diversity in land plants is multifaceted and that matrix glycan epitopes display complex spatio-temporal and phylogenetic distribution patterns that are likely to relate to the evolution of land plant body plans. [ABSTRACT FROM AUTHOR]