Arabinogalactan-proteins (AGPs) are undoubtedly one of the most complex families of macromolecules found in plants, perhaps matched only by the polyphenolics (lignins/cutins/suberins) and pectins. Their complexity arises from the incredible diversity of the glycans decorating the protein backbone,

Arabinogalactan-Proteins: Key Regulators at the Cell Surface?

A biotechnological perspective on the application of iron oxide magnetic colloids modified with polysaccharides

There is a great deal of interest in the Food Industry in the use of polysaccharides and proteins to stabilise oil-in-water emulsions and there is particular interest nowadays in the use of polysaccharide–protein complexes. There are three classes of complexes namely; (a) naturally-occurring complexes in which protein residues are covalently attached to the polysaccharide chains as is the case, for example, with gum Arabic; (b) Maillard conjugates, which are formed by interaction of the reducing end of a polysaccharide with an amine group on a protein forming a covalent bond; and (c) electrostatic complexes formed between a polysaccharide and a protein with opposite net charge. This review sets out our current understanding of the nature of these different polysaccharide-protein complexes and their ability to stabilise oil-in-water emulsions.

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Emulsion stabilization using polysaccharide-protein complexes

Biopolymer nano- and micro-particles, fabricated from either proteins and/or polysaccharides, can be utilized as delivery systems or to modulate the physicochemical and sensory characteristics of food products. This article reviews the principles underlying the design, fabrication, and application of biopolymer particles fabricated from globular proteins, used either alone or in combination with polysaccharides, within the food industry. The properties of biopolymer particles and their impact on the physicochemical and functional properties of foods are described. The molecular characteristics and interactions of the building blocks (proteins and polysaccharides) used to assemble these particles are briefly reviewed. The major structural design principles that can be used to fabricate biopolymer particles from food-grade proteins and polysaccharides are outlined. Finally, some of the potential applications of functional biopolymer particles within foods are highlighted.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1541-4337.2010.00118.x

Functional Biopolymer Particles: Design, Fabrication, and Applications.

Synthesis and antioxidant properties of gum arabic-stabilized selenium nanoparticles.

The structural characteristics of the gum exudate of Acacia senegal (gum arabic) have been investigated by monitoring the composition and physicochemical properties before and after treatment with proteolytic enzyme and various alkaline systems. Molecular mass ( M w) and radius of gyration ( R g) measurements were performed using gel permeation chromatography (GPC) coupled to refractive index, UV absorbance, and multiangle light scattering detectors and indicated that the macromolecules present have a compact structure. It was found that treatment with proteolytic enzyme caused the arabinogalactan-protein component (AGP) with average molecular mass approximately 2 x 10 (6) Da to degrade, yielding material of molecular mass approximately 4 x 10 (5) Da, whereas the bulk of the material corresponding to the protein-deficient arabinogalactan component (AG) with molecular mass 4 x 10 (5) remained unaffected. Barium hydroxide was found to hydrolyze the polysaccharide component (AG) itself in addition to the proteinaceous component as demonstrated in control experiments using dextran. However, sodium borohydride/sodium hydroxide treatments were unable to hydrolyze dextran and were assumed to hydrolyze only the proteinaceous component of gum arabic. The AGP component was completely degraded, yielding material of molecular mass approximately 4.5 x 10 (4) Da. It has been concluded, therefore, that the enzyme did not fully hydrolyze all of the protein present and that the AGP component of gum arabic consists of carbohydrate blocks of approximately 4.5 x 10 (4) Da linked to a polypeptide chain consistent with the wattle blossom structure. Because the AGP was degraded to differing extents using a mild and more severe sodium borohydride/sodium hydroxide treatment, it was concluded that the polysaccharide moieties were linked through both O-serine and O-hydroxyproline residues. The gum arabic sample was deglycosylated by treatment with anhydrous hydrogen fluoride and revealed the presence of two putative core proteins of approximately 3 x 10 (4) and approximately 5 x 10 (3) Da, respectively, which correspond to proteins of approximately 250 and 45 amino acids in length. A new model for the structure of the AGP component has been proposed.

T Mahendran

Papers

New insights into the structural characteristics of the arabinogalactan-protein (AGP) fraction of gum arabic.