Arabinogalactans Research Articles

Peculiarities and applications of galactanolytic enzymes that act on type I and II arabinogalactans

Arabinogalactans (AGs) are branched galactans to which arabinose residues are bound as side chains and are widely distributed in plant cell walls. They can be grouped into two types based on the structures of their backbones. Type I AGs have β-1,4-galactan backbones and are often covalently linked to the rhamnogalacturonan-I region of pectins. Type II AGs have β-1,3-galactan backbones and are often covalently linked to proteins. The main enzymes involved in the degradation of AGs are endo-β-galactanases, exo-β-galactanases, and β-galactosidases, although other enzymes such as α-L-arabinofuranosidases, β-L-arabinopyranosidases, and β-D-glucuronidases are required to remove the side chains for efficient degradation of the polysaccharides. Galactanolytic enzymes have a wide variety of potential uses, including the bioconversion of AGs to fermentable sugars for production of commodity chemicals like ethanol, biobleaching of cellulose pulp, modulation of pectin properties, improving animal feed, and determining the chemical structure of AGs. This review summarizes our current knowledge about the biochemical properties and potential applications of AG-degrading enzymes.

SECONDARY EFFECTS IN AQUEOUS SIZE-EXCLUSION CHROMATOGRAPHY OF POLYSACCHARIDES

This paper’s main concern is with the investigation of the elution properties of water-soluble polysaccharides in Size-exclusion chromatography (SEC) using multiangle laser light scattering and differential refractive index detectors in aqueous solvents. Chromatographic data on influence of nature of solvent to the formation of polymer aggregates is presented. We have shown that in pure water as eluent the bimodal and multimodal chromatograms of Na-carboxymethylcellulose (Na-CMC) and arabinogalactans (AG) were received. This phenomenon indicates of presence of intermolecular enthalpic interactions in solutions. We found that aqueous eluents containing 0,1 M NaCl for Na-CMC and 0,14 M NaNO3 for AG are preferred to prevent of secondary effects distorting of SEC separation mechanism.

Isolation and characterisation of arabinogalactan-proteins from New Zealand kanuka honey

Fractionation of manuka, kanuka and clover honeys indicated the >10kDa fraction contained small amounts of type II arabinogalactans (AGs), which are often present as arabinogalactan proteins (AGPs). AGPs were isolated from the >10kDa fraction of kanuka honey using β-glucosyl Yariv reagent and their composition and structure analysed. Constituent sugar, glycosyl linkage and NMR spectroscopy analysis of the purified AGP fraction revealed a predominance of neutral sugars, mainly galactose and arabinose, linked in a highly-branched structure typical of type II AGs. The molecular weight of the major component of the purified AGPs was ∼110kDa, as determined by size-exclusion chromatography-multi-angle laser light scattering (SEC-MALLS). The Yariv supernatant fraction contained less total sugar, especially galactose, and more protein than purified AGPs. Linkage analysis indicated this fraction also contained an AG-type polymer in addition to various other polysaccharides and SEC-MALLS indicated the molecular weight of the major component was ∼32kDa.

Selective Hydrolysis of Arabinogalactan into Arabinose and Galactose Over Heterogeneous Catalysts

The application of solid acid catalysts for the production of monomers from hemicelluloses can be one of the key steps in developing the concept of an integrated forest biorefinery. Arabinogalactans (AG) are hemicelluloses which can be extracted on an industrial scale from larch wood species and has a great potential as a sustainable feedstock for bio-based products. Hydrolysis of AG to monomers over acidic heterogeneous catalysts (Smopex-101 and Amberlyst 15) was successfully demonstrated for the first time to selectively produce arabinose as the primary product, followed by the release of galactose without further degradation of the monomers. Selective hydrolysis of arabinogalactan into arabinose and galactose over heterogeneous catalysts

Kinetics of Acid Hydrolysis of Arabinogalactans

The kinetics of the acid hydrolysis of arabinogalactans (AG) was studied isothermally in a batch reactor. AG was hydrolyzed with hydrochloric acid and the main parameters established were the acid concentration (pH), temperature and AG concentration. The hydrolysis rate increased with the acid concentration (pH) and temperature. Complete hydrolysis of AG to arabinose and galactose was achieved at 90°C and pH 1 without any further degradation of the sugars. A first-order kinetic model including two simultaneous reactions for the formation of arabinose and galactose was successfully fitted to the experimental data. The rate constants and activation energies were calculated from the model. The decrease of the average molecular weight was also explained by the model.

An Efficient Method for the Synthesis of 2,6‐Branched Galacto‐Oligosaccharides and Its Applications to the Synthesis of Three Tetrasaccharides and a Hexasaccharide Related to the Arabinogalactans (AGs).

ChemInformVolume 35, Issue 8 Natural Products An Efficient Method for the Synthesis of 2,6-Branched Galacto-Oligosaccharides and Its Applications to the Synthesis of Three Tetrasaccharides and a Hexasaccharide Related to the Arabinogalactans (AGs). Jun Ning, Jun Ning Res. Cent. Eco-Environ. Sci., Acad. Sin., Beijing 100085, Peop. Rep. ChinaSearch for more papers by this authorYuetao Yi, Yuetao Yi Res. Cent. Eco-Environ. Sci., Acad. Sin., Beijing 100085, Peop. Rep. ChinaSearch for more papers by this authorZhe Zao, Zhe Zao Res. Cent. Eco-Environ. Sci., Acad. Sin., Beijing 100085, Peop. Rep. ChinaSearch for more papers by this author Jun Ning, Jun Ning Res. Cent. Eco-Environ. Sci., Acad. Sin., Beijing 100085, Peop. Rep. ChinaSearch for more papers by this authorYuetao Yi, Yuetao Yi Res. Cent. Eco-Environ. Sci., Acad. Sin., Beijing 100085, Peop. Rep. ChinaSearch for more papers by this authorZhe Zao, Zhe Zao Res. Cent. Eco-Environ. Sci., Acad. Sin., Beijing 100085, Peop. Rep. ChinaSearch for more papers by this author First published: 28 January 2004 https://doi.org/10.1002/chin.200408206AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume35, Issue8February 24, 2004 RelatedInformation

An Efficient Method for the Synthesis of 2,6-Branched Galacto-Oligo­saccharides and Its Applications to the Synthesis of Three Tetrasaccharides and a Hexasaccharide Related to the Arabinogalactans (AGs)

An efficient method for the synthesis of 2,6-branched galacto-oligosaccharides has been developed by using 6-O-Ac-2,3,4-tri-O-Bz-α-D-galactopyranosyl trichloroacetimidate, 2,6-di-O-Ac-3,4-di-O-Bz-a-D-galactopyranosyl trichloroacetimidate and 2-O-Ac-3,4,6-tri-O-Bz-a-D-galactopyranosyl trichloroacetimidate as synthons. Three tetrasaccharides and a hexasaccharides related to AGs from plants were readily prepared using this method.

A Simple Approach to 3,6‐Branched Galacto‐Oligosaccharides and Its Application to the Syntheses of a Tetrasaccharide and a Hexasaccharide Related to the Arabinogalactans (AGs).

Abstract The preparation of 1,2:5,6-di- O -isopropylidene-α- d -galactofuranose was improved by increasing the ratio of DMF to acetone and using a solid supported catalyst. Employing the easily accessible 1,2:5,6-di- O -isopropylidene-α- d -galactofuranose as the starting glycosyl acceptor, a method which is particularly suitable for the regio- and stereoselective syntheses of 3,6-branched galacto-oligosaccharides was developed. A tetrasaccharide and a hexasaccharide related to the arabinogalactans (AGs) from plants were readily prepared using this strategy.

A simple approach to 3,6-branched galacto-oligosaccharides and its application to the syntheses of a tetrasaccharide and a hexasaccharide related to the arabinogalactans (AGs)

The preparation of 1,2:5,6-di- O-isopropylidene-α- d-galactofuranose was improved by increasing the ratio of DMF to acetone and using a solid supported catalyst. Employing the easily accessible 1,2:5,6-di- O-isopropylidene-α- d-galactofuranose as the starting glycosyl acceptor, a method which is particularly suitable for the regio- and stereoselective syntheses of 3,6-branched galacto-oligosaccharides was developed. A tetrasaccharide and a hexasaccharide related to the arabinogalactans (AGs) from plants were readily prepared using this strategy.