Structural insight of an antioxidative arabinogalactan protein of Aegle marmelos fruit gum and it's interaction with β-lactoglobulin

The complication of arabinogalactan protein (AGP) structure, a significant ingredient of gum polysaccharides, not merely hinders the allocation of its role, but restricts its utilization as well. Here, we describe structural details of an AGP purified from Aegle marmelos fruit gum. This AGP (310 × 103 g/mol), which is water-soluble, contains β-1,3-linked galactopyranosyl main chain substituted at O-6 position with side chains containing galactose and arabinose residues. Also data on sugar composition, ring size, glycosidic linkage pattern, anomeric configuration and sequence of monosaccharide units of a number of oligosaccharides produced from this AGP by chemical and enzymatic methods were acquired. Biochemical analysis reveals resemblance in antioxidative potential between this arabinogalactan protein and standard antioxidants. Moreover, mixture of AGP and β-lactoglobulin form stable water soluble complex having binding constant K = 2.38 × 106/M. As gum polysaccharides are important raw materials of food industry discovering an antioxidative gum with the ability of creating stable water soluble complex with β-lactoglobulin may have important implication.