Molecular association and function of arabinogalactan protein complexes from tree exudates

Abstract

Gum arabic is an exudate from the Acacia trees found in the arid conditions of the Sahelian belts of Africa. The particular gum discussed here is from the species Acacia senegal is a complex polydisperse molecule and is widely used in the food industry, mainly as a natural emulsifier. It is the high molecular weight arabinogalactan protein (AGP) component which is responsible for its emulsification functionality. A process is described which can increase the content and molecular weight of this component and as a result a new series of commercial gum arabic products have been produced, designated Acacia senegal(sey)SUPERGUM. The maturation process used to prepare these products is similar to that which occurs in the natural state of the tree. The paper describes how aggregation of the AGP can be controlled whereby low molecular weight components can be associated to form stable products. The mechanism of this association is discussed and explained in terms of inter-molecular equilibria. The results satisfactorily account for the large variation found in natural gum arabic and in commercial samples. Since this molecular variation can adversely affect the effectiveness of the gum arabic as an emulsifier, it is important that it can now be standardized and enhanced. There are indications that the basic building block of Acacia senegal is ca 400,000 Da but that aggregates of this unit can form depending on local conditions and commercial processing methods.

Chemical and physicochemical characterizations of the water-soluble fraction of the Commiphora Africana exudate

“…All the average parameters (on the whole elution time range) are summarized in Table 4. Mw is about 1 300 000 g.mol -1 while Mn is 260 000 g.mol -1 , proving that the system is highly polydisperse as it is often observed for natural polysaccharide from plants (Eagles, Stephen, & Churms, 1993); (Phillips, 2009). In addition, thanks to viscosimetric detector, the intrinsic viscosity was determined and is very close to the one measured by the rolling ball viscometer.…”

“…This suggests that the three population own covalently bonded protein with similar ratio, proving that bonded proteins are homogeneously distributed between the three populations. This is an unusual property, very different to what is observed for gums containing glycoproteins such as acacia gum for instance (Phillips, 2009) but that were already found for closely related Myrrh gum (Commiphora molmol) (Wiendl et al, 1995).…”

Gum Arabic coated magnetic nanoparticles with affinity ligands specific for antibodies

“…Magnetic adsorbents are an effective alternative in bioseparation processes, including antibody purification (Quitadamo and Schelling, 1998; Holschuh and Schwämmle, 2005). Additionally, these materials can find applications in other important biotechnological areas such as therapeutics, diagnostics, and biosensing (Yu et al , 2008; Xu and Sun, 2009).…”

Physicochemical and in vitro biocompatibility of films combining reconstituted bacterial cellulose with arabinogalactan and xyloglucan

“…Arabinogalactans are macromolecules containing arabinose and galactose that are found in most plant tissues (Cipriani, Mellinger, Gorin, & Iacomini, 2004;Phillips, 2009;Sierakowski, Gorin, Reicher, & Corrêa, 1987, 1990Wang, Burchard, Cui, Huang, & Phillips, 2008;Yang, Prasad, & Jiang, 2016). Their abundance, ubiquitous distribution and location within plant cells suggest that they perform different functions at cellular and sub-cellular levels (Redgwell, Schmitt, Beaulieu, & Curti, 2005).…”